1. Factorial program in cFactorial program in c: c code to find and print factorial of a number, three methods are given, first one uses for loop, second uses a function to find factorial and third using recursion. Factorial is represented using '!', so five factorial will be written as (5!), n factorial as (n!). Alson! = n*(n-1)*(n-2)*(n-3)...3.2.1 and zero factorial is defined as one i.e. 0! = 1.

#include <stdio.h> int main()
{
int c, n, fact = 1; printf("Enter a number to calculate it's factorial\n"); scanf("%d", &n); for (c = 1; c <= n; c++) fact = fact * c; printf("Factorial of %d = %d\n", n, fact); return 0;
}

2. c program to check odd or evenc program to check odd or even: We will determine whether a number is odd or even by using different methods all are provided with a code in c language. As you have study in mathematics that in decimal number system even numbers are divisible by 2 while odd are not so we may use modulus operator(%) which returns remainder, For example 4%3 gives 1 ( remainder when four is divided by three). Even numbers are of the form 2*p and odd are of the form (2*p+1) where p is is an integer.

#include<stdio.h> main()
{
int n; printf("Enter an integer\n"); scanf("%d",&n); if ( n%2 == 0 ) printf("Even\n"); else printf("Odd\n"); return 0;
}

3. C program to check whether input alphabet is a vowel or notThis code checks whether an input alphabet is a vowel or not. Both lower-case and upper-case are checked.

#include <stdio.h> int main()
{
char ch; printf("Enter a character\n"); scanf("%c", &ch); if (ch == 'a' || ch == 'A' || ch == 'e' || ch == 'E' || ch == 'i' || ch == 'I' || ch =='o' || ch=='O' || ch == 'u' || ch == 'U') printf("%c is a vowel.\n", ch); else printf("%c is not a vowel.\n", ch); return 0;
}

4. C program to check leap yearC program to check leap year: c code to check leap year, year will be entered by the user.

#include <stdio.h> int main()
{
int year; printf("Enter a year to check if it is a leap year\n"); scanf("%d", &year); if ( year%400 == 0) printf("%d is a leap year.\n", year); else if ( year%100 == 0) printf("%d is not a leap year.\n", year); else if ( year%4 == 0 ) printf("%d is a leap year.\n", year); else printf("%d is not a leap year.\n", year); return 0;

5. Decimal to binary conversionC program to convert decimal to binary: c language code to convert an integer from decimal number system(base-10) to binary number system(base-2). Size of integer is assumed to be 32 bits. We use bitwise operators to perform the desired task. We right shift the original number by 31, 30, 29, ..., 1, 0 bits using a loop and bitwise AND the number obtained with 1(one), if the result is 1 then that bit is 1 otherwise it is 0(zero).

#include <stdio.h> int main()
{
int n, c, k; printf("Enter an integer in decimal number system\n"); scanf("%d", &n); printf("%d in binary number system is:\n", n); for (c = 31; c >= 0; c--) { k = n >> c; if (k & 1) printf("1"); else printf("0"); } printf("\n"); return 0;
}

6. C program to swap two numbersC program to swap two numbers with and without using third variable, swapping in c using pointers, functions (Call by reference) and using bitwise XOR operator, swapping means interchanging. For example if in your c program you have taken two variable a and b where a = 4 and b = 5, then before swapping a = 4, b = 5 after swapping a = 5, b = 4In our c program to swap numbers we will use a temp variable to swap two numbers.

#include <stdio.h> int main()
{
int x, y, temp; printf("Enter the value of x and y\n"); scanf("%d%d", &x, &y); printf("Before Swapping\nx = %d\ny = %d\n",x,y); temp = x; x = y; y = temp; printf("After Swapping\nx = %d\ny = %d\n",x,y); return 0;
}

7. C program to reverse a numberC Program to reverse a number :- This program reverse the number entered by the user and then prints the reversed number on the screen. For example if user enter 123 as input then 321 is printed as output. In our program we use modulus(%) operator to obtain the digits of a number. To invert number look at it and write it from opposite direction or the output of code is a number obtained by writing original number from right to left. To reverse or invert large numbers use long data type or long long data type if your compiler supports it, if you still have large numbers then use strings or other data structure.

#include <stdio.h> int main()
{
int n, reverse = 0; printf("Enter a number to reverse\n"); scanf("%d",&n); while (n != 0) { reverse = reverse * 10; reverse = reverse + n%10; n = n/10; } printf("Reverse of entered number is = %d\n", reverse); return 0;
}

8. Palindrome NumbersPalindrome number in c: A palindrome number is a number such that if we reverse it, it will not change. For example some palindrome numbers examples are 121, 212, 12321, -454. To check whether a number is palindrome or not first we reverse it and then compare the number obtained with the original, if both are same then number is palindrome otherwise not. C program for palindrome number is given below.
Palindrome number algorithm1. Get the number from user.2. Reverse it.3. Compare it with the number entered by the user.4. If both are same then print palindrome number5. Else print not a palindrome number.

#include <stdio.h> int main()
{
int n, reverse = 0, temp; printf("Enter a number to check if it is a palindrome or not\n"); scanf("%d",&n); temp = n; while( temp != 0 ) { reverse = reverse * 10; reverse = reverse + temp%10; temp = temp/10; } if ( n == reverse ) printf("%d is a palindrome number.\n", n); else printf("%d is not a palindrome number.\n", n); return 0;
}

9. C program to print patterns of numbers and starsThese program prints various different patterns of numbers and stars. These codes illustrate how to create various patterns using c programming. Most of these c programs involve usage of nested loops and space. A pattern of numbers, star or characters is a way of arranging these in some logical manner or they may form a sequence. Some of these patterns are triangles which have special importance in mathematics. Some patterns are symmetrical while other are not. Please see the complete page and look at comments for many different patterns. * *** ***** *******
*********
We have shown five rows above, in the program you will be asked to enter the numbers of rows you want to print in the pyramid of stars.

#include <stdio.h> int main()
{
int row, c, n, temp; printf("Enter the number of rows in pyramid of stars you wish to see "); scanf("%d",&n); temp = n; for ( row = 1 ; row <= n ; row++ ) { for ( c = 1 ; c < temp ; c++ ) printf(" "); temp--; for ( c = 1 ; c <= 2*row - 1 ; c++ ) printf("*"); printf("\n"); } return 0;
}

Consider the pattern*************** to print above pattern see the code below:
#include <stdio.h> int main()
{
int n, c, k; printf("Enter number of rows\n"); scanf("%d",&n); for ( c = 1 ; c <= n ; c++ ) { for( k = 1 ; k <= c ; k++ ) printf("*"); printf("\n"); } return 0;
}
Using these examples you are in a better position to create your desired pattern for yourself. Creating a pattern involves how to use nested loops properly, some pattern may involve alphabets or other special characters. Key aspect is knowing how the characters in pattern changes.
C pattern programsPattern: * *A* *A*A*
*A*A*A*
#include<stdio.h> main()
{
int n, c, k, space, count = 1; printf("Enter number of rows\n"); scanf("%d",&n); space = n; for ( c = 1 ; c <= n ; c++) { for( k = 1 ; k < space ; k++) printf(" "); for ( k = 1 ; k <= c ; k++) { printf("*"); if ( c > 1 && count < c) { printf("A"); count++; } } printf("\n"); space--; count = 1; } return 0;
}
Pattern: 1 232 34543 4567654 567898765
#include<stdio.h>

main()
{
int n, c, d, num = 1, space; scanf("%d",&n); space = n - 1; for ( d = 1 ; d <= n ; d++ ) { num = d; for ( c = 1 ; c <= space ; c++ ) printf(" "); space--; for ( c = 1 ; c <= d ; c++ ) { printf("%d", num); num++; } num--; num--; for ( c = 1 ; c < d ; c++) { printf("%d", num); num--; } printf("\n"); } return 0;
}

10. C program to print Floyd's triangleC program to print Floyd's triangle:- This program prints Floyd's triangle. Number of rows of Floyd's triangle to print is entered by the user. First four rows of Floyd's triangle are as follows :-12 34 5 67 8 9 10It's clear that in Floyd's triangle nth row contains n numbers.

#include <stdio.h> int main()
{
int n, i, c, a = 1; printf("Enter the number of rows of Floyd's triangle to print\n"); scanf("%d", &n); for (i = 1; i <= n; i++) { for (c = 1; c <= i; c++) { printf("%d ",a); a++; } printf("\n"); } return 0;
}

11. C program to print Pascal trianglePascal Triangle in c: C program to print Pascal triangle which you might have studied in Binomial Theorem in Mathematics. Number of rows of Pascal triangle to print is entered by the user. First four rows of Pascal triangle are shown below :- 1 1 1 1 2 1
1 3 3 1
#include <stdio.h> long factorial(int); int main()
{
int i, n, c; printf("Enter the number of rows you wish to see in pascal triangle\n"); scanf("%d",&n); for ( i = 0 ; i < n ; i++ ) { for ( c = 0 ; c <= ( n - i - 2 ) ; c++ ) printf(" "); for( c = 0 ; c <= i ; c++ ) printf("%ld ",factorial(i)/(factorial(c)*factorial(i-c))); printf("\n"); } return 0;
}

long factorial(int n)
{
int c; long result = 1; for( c = 1 ; c <= n ; c++ ) result = result*c; return ( result );
}

12. C program to print diamond patternDiamond pattern in c: This code print diamond pattern of stars. Diamond shape is as follows: * ***
*****
*** *
#include <stdio.h> int main()
{
int n, c, k, space = 1; printf("Enter number of rows\n"); scanf("%d", &n); space = n - 1; for (k = 1; k <= n; k++) { for (c = 1; c <= space; c++) printf(" "); space--; for (c = 1; c <= 2*k-1; c++) printf("*"); printf("\n"); } space = 1; for (k = 1; k <= n - 1; k++) { for (c = 1; c <= space; c++) printf(" "); space++; for (c = 1 ; c <= 2*(n-k)-1; c++) printf("*"); printf("\n"); } return 0;
}

13. C program for prime numberPrime number program in c: c program for prime number, this code prints prime numbers using c programming language. To check whether a number is prime or not see another code below. Prime number logic: a number is prime if it is divisible only by one and itself. Remember two is the only even and also the smallest prime number. First few prime numbers are 2, 3, 5, 7, 11, 13, 17....etc. Prime numbers have many applications in computer science and mathematics. A number greater than one can be factorized into prime numbers, For example 540 = 22*33*51

#include<stdio.h> int main()
{
int n, i = 3, count, c; printf("Enter the number of prime numbers required\n"); scanf("%d",&n); if ( n >= 1 ) { printf("First %d prime numbers are :\n",n); printf("2\n"); } for ( count = 2 ; count <= n ; ) { for ( c = 2 ; c <= i - 1 ; c++ ) { if ( i%c == 0 ) break; } if ( c == i ) { printf("%d\n",i); count++; } i++; } return 0;
}

14. C program for prime number or not#include<stdio.h> main()
{
int n, c = 2; printf("Enter a number to check if it is prime\n"); scanf("%d",&n); for ( c = 2 ; c <= n - 1 ; c++ ) { if ( n%c == 0 ) { printf("%d is not prime.\n", n); break; } } if ( c == n ) printf("%d is prime.\n", n); return 0;
}

15. Armstrong number c programArmstrong number c program: c programming code to check whether a number is armstrong or not. A number is armstrong if the sum of cubes of individual digits of a number is equal to the number itself. For example 371 is an armstrong number as 33 + 73 + 13 = 371. Some other armstrong numbers are: 0, 1, 153, 370, 407.

#include <stdio.h> int main()
{
int number, sum = 0, temp, remainder; printf("Enter an integer\n"); scanf("%d",&number); temp = number; while( temp != 0 ) { remainder = temp%10; sum = sum + remainder*remainder*remainder; temp = temp/10; } if ( number == sum ) printf("Entered number is an armstrong number.\n"); else printf("Entered number is not an armstrong number.\n"); return 0;
}

16. Fibonacci series in cFibonacci series in c programming: c program for Fibonacci series without and with recursion. Using the code below you can print as many numbers of terms of series as desired. Numbers of Fibonacci sequence are known as Fibonacci numbers. First few numbers of series are 0, 1, 1, 2, 3, 5, 8 etc, Except first two terms in sequence every other term is the sum of two previous terms, For example 8 = 3 + 5 (addition of 3, 5). This sequence has many applications in mathematics and Computer Science.

#include<stdio.h> int main()
{
int n, first = 0, second = 1, next, c; printf("Enter the number of terms\n"); scanf("%d",&n); printf("First %d terms of Fibonacci series are :-\n",n); for ( c = 0 ; c < n ; c++ ) { if ( c <= 1 ) next = c; else { next = first + second; first = second; second = next; } printf("%d\n",next); } return 0;
}

17. C program to add two numbers using pointersThis program performs addition of two numbers using pointers. In our program we have two two integer variables x, y and two pointer variables p and q. Firstly we assign the addresses of x and y to p and q respectively and then assign the sum of x and y to variable sum. Note that & is address of operator and * is value at address operator.

#include <stdio.h> int main()
{
int first, second, *p, *q, sum; printf("Enter two integers to add\n"); scanf("%d%d", &first, &second); p = &first; q = &second; sum = *p + *q; printf("Sum of entered numbers = %d\n",sum); return 0;
}

18. C program to find maximum element in arrayThis code find maximum or largest element present in an array. It also prints the location or index at which maximum element occurs in array. This can also be done by using pointers (see both codes).

#include <stdio.h> int main()
{
int array[100], maximum, size, c, location = 1; printf("Enter the number of elements in array\n"); scanf("%d", &size); printf("Enter %d integers\n", size); for (c = 0; c < size; c++) scanf("%d", &array[c]); maximum = array[0]; for (c = 1; c < size; c++) { if (array[c] > maximum) { maximum = array[c]; location = c+1; } } printf("Maximum element is present at location %d and it's value is %d.\n", location, maximum); return 0;
}

19. C program to find minimum element in arrayC code to find minimum or smallest element present in an array. It also prints the location or index at which minimum element occurs in array. This can also be done by using pointers (see both the codes).
#include <stdio.h> int main()
{
int array[100], minimum, size, c, location = 1; printf("Enter the number of elements in array\n"); scanf("%d",&size); printf("Enter %d integers\n", size); for ( c = 0 ; c < size ; c++ ) scanf("%d", &array[c]); minimum = array[0]; for ( c = 1 ; c < size ; c++ ) { if ( array[c] < minimum ) { minimum = array[c]; location = c+1; } } printf("Minimum element is present at location %d and it's value is %d.\n", location, minimum); return 0;
}

20. Linear search in cLinear search in c programming: The following code implements linear search (Searching algorithm) which is used to find whether a given number is present in an array and if it is present then at what location it occurs. It is also known as sequential search. It is very simple and works as follows: We keep on comparing each element with the element to search until the desired element is found or list ends. Linear search in c language for multiple occurrences and using function.
#include <stdio.h> int main()
{
int array[100], search, c, n; printf("Enter the number of elements in array\n"); scanf("%d",&n); printf("Enter %d integer(s)\n", n); for (c = 0; c < n; c++) scanf("%d", &array[c]); printf("Enter the number to search\n"); scanf("%d", &search); for (c = 0; c < n; c++) { if (array[c] == search) /* if required element found */ { printf("%d is present at location %d.\n", search, c+1); break; } } if (c == n) printf("%d is not present in array.\n", search); return 0;
}

21. C program for binary searchC program for binary search: This code implements binary search in c language. It can only be used for sorted arrays, but it's fast as compared to linear search. If you wish to use binary search on an array which is not sorted then you must sort it using some sorting technique say merge sort and then use binary search algorithm to find the desired element in the list. If the element to be searched is found then its position is printed.

#include <stdio.h> int main()
{
int c, first, last, middle, n, search, array[100]; printf("Enter number of elements\n"); scanf("%d",&n); printf("Enter %d integers\n", n); for ( c = 0 ; c < n ; c++ ) scanf("%d",&array[c]); printf("Enter value to find\n"); scanf("%d",&search); first = 0; last = n - 1; middle = (first+last)/2; while( first <= last ) { if ( array[middle] < search ) first = middle + 1; else if ( array[middle] == search ) { printf("%d found at location %d.\n", search, middle+1); break; } else last = middle - 1; middle = (first + last)/2; } if ( first > last ) printf("Not found! %d is not present in the list.\n", search); return 0;
}

22. C program to reverse an arrayC program to reverse an array: This program reverses the array elements. For example if a is an array of integers with three elements such thata[0]=1a[1]=2a[2]=3Then on reversing the array will bea[0]=3a[1]=2a[0]=1

#include <stdio.h> int main()
{
int n, c, d, a[100], b[100]; printf("Enter the number of elements in array\n"); scanf("%d", &n); printf("Enter the array elements\n"); for (c = 0; c < n ; c++) scanf("%d", &a[c]); /* * Copying elements into array b starting from end of array a */ for (c = n - 1, d = 0; c >= 0; c--, d++) b[d] = a[c]; /* * Copying reversed array into original. * Here we are modifying original array, this is optional. */ for (c = 0; c < n; c++) a[c] = b[c]; printf("Reverse array is\n"); for (c = 0; c < n; c++) printf("%d\n", a[c]); return 0;
}

23. C program to insert an element in an arrayThis code will insert an element into an array, For example consider an array a[10] having three elements in it initially and a[0] = 1, a[1] = 2 and a[2] = 3 and you want to insert a number 45 at location 1 i.e. a[0] = 45, so we have to move elements one step below so after insertion a[1] = 1 which was a[0] initially, and a[2] = 2 and a[3] = 3. Array insertion does not mean increasing its size i.e array will not be containing 11 elements.
#include <stdio.h> int main()
{
int array[100], position, c, n, value; printf("Enter number of elements in array\n"); scanf("%d", &n); printf("Enter %d elements\n", n); for (c = 0; c < n; c++) scanf("%d", &array[c]); printf("Enter the location where you wish to insert an element\n"); scanf("%d", &position); printf("Enter the value to insert\n"); scanf("%d", &value); for (c = n - 1; c >= position - 1; c--) array[c+1] = array[c]; array[position-1] = value; printf("Resultant array is\n"); for (c = 0; c <= n; c++) printf("%d\n", array[c]); return 0;
}

24. C program to delete an element from an arrayThis program delete an element from an array. Deleting an element does not affect the size of array. It is also checked whether deletion is possible or not, For example if array is containing five elements and you want to delete element at position six which is not possible.
#include <stdio.h> int main()
{
int array[100], position, c, n; printf("Enter number of elements in array\n"); scanf("%d", &n); printf("Enter %d elements\n", n); for ( c = 0 ; c < n ; c++ ) scanf("%d", &array[c]); printf("Enter the location where you wish to delete element\n"); scanf("%d", &position); if ( position >= n+1 ) printf("Deletion not possible.\n"); else { for ( c = position - 1 ; c < n - 1 ; c++ ) array[c] = array[c+1]; printf("Resultant array is\n"); for( c = 0 ; c < n - 1 ; c++ ) printf("%d\n", array[c]); } return 0;
}

25. C program to merge two arraysC program to merge two arrays into third array: Arrays are assumed to be sorted inascending order. You enter two short sorted arrays and combine them to get a large array.

#include <stdio.h> void merge(int [], int, int [], int, int []); int main() { int a[100], b[100], m, n, c, sorted[200]; printf("Input number of elements in first array\n"); scanf("%d", &m); printf("Input %d integers\n", m); for (c = 0; c < m; c++) { scanf("%d", &a[c]); } printf("Input number of elements in second array\n"); scanf("%d", &n); printf("Input %d integers\n", n); for (c = 0; c < n; c++) { scanf("%d", &b[c]); } merge(a, m, b, n, sorted); printf("Sorted array:\n"); for (c = 0; c < m + n; c++) { printf("%d\n", sorted[c]); } return 0;
}

void merge(int a[], int m, int b[], int n, int sorted[]) { int i, j, k; j = k = 0; for (i = 0; i < m + n;) { if (j < m && k < n) { if (a[j] < b[k]) { sorted[i] = a[j]; j++; } else { sorted[i] = b[k]; k++; } i++; } else if (j == m) { for (; i < m + n;) { sorted[i] = b[k]; k++; i++; } } else { for (; i < m + n;) { sorted[i] = a[j]; j++; i++; } } }
}

26. C program for bubble sortC program for bubble sort: c programming code for bubble sort to sort numbers or arrange them in ascending order. You can easily modify it to print numbers in descending order. #include <stdio.h> int main()
{
int array[100], n, c, d, swap; printf("Enter number of elements\n"); scanf("%d", &n); printf("Enter %d integers\n", n); for (c = 0; c < n; c++) scanf("%d", &array[c]); for (c = 0 ; c < ( n - 1 ); c++) { for (d = 0 ; d < n - c - 1; d++) { if (array[d] > array[d+1]) /* For decreasing order use < */ { swap = array[d]; array[d] = array[d+1]; array[d+1] = swap; } } } printf("Sorted list in ascending order:\n"); for ( c = 0 ; c < n ; c++ ) printf("%d\n", array[c]); return 0;
}

27. insertion sort in cInsertion sort in c: c program for insertion sort to sort numbers. This code implements insertion sort algorithm to arrange numbers of an array in ascending order. With a little modification it will arrange numbers in descending order. #include <stdio.h> int main()
{
int n, array[1000], c, d, t; printf("Enter number of elements\n"); scanf("%d", &n); printf("Enter %d integers\n", n); for (c = 0; c < n; c++) { scanf("%d", &array[c]); } for (c = 1 ; c <= n - 1; c++) { d = c; while ( d > 0 && array[d] < array[d-1]) { t = array[d]; array[d] = array[d-1]; array[d-1] = t; d--; } } printf("Sorted list in ascending order:\n"); for (c = 0; c <= n - 1; c++) { printf("%d\n", array[c]); } return 0;
}

28. Selection sort in cSelection sort in c: c program for selection sort to sort numbers. This code implements selection sort algorithm to arrange numbers of an array in ascending order. With a little modification it will arrange numbers in descending order.
#include <stdio.h> int main()
{
int array[100], n, c, d, position, swap; printf("Enter number of elements\n"); scanf("%d", &n); printf("Enter %d integers\n", n); for ( c = 0 ; c < n ; c++ ) scanf("%d", &array[c]); for ( c = 0 ; c < ( n - 1 ) ; c++ ) { position = c; for ( d = c + 1 ; d < n ; d++ ) { if ( array[position] > array[d] ) position = d; } if ( position != c ) { swap = array[c]; array[c] = array[position]; array[position] = swap; } } printf("Sorted list in ascending order:\n"); for ( c = 0 ; c < n ; c++ ) printf("%d\n", array[c]); return 0;
}

29. c program to add two matrixThis c program add two matrices i.e. compute the sum of two matrices and then print it. Firstly user will be asked to enter the order of matrix ( number of rows and columns ) and then two matrices. For example if the user entered order as 2, 2 i.e. two rows and two columns and matrices asFirst Matrix :-1 23 4Second matrix :-4 5-1 5then output of the program ( sum of First and Second matrix ) will be5 72 9
#include <stdio.h> int main()
{
int m, n, c, d, first[10][10], second[10][10], sum[10][10]; printf("Enter the number of rows and columns of matrix\n"); scanf("%d%d", &m, &n); printf("Enter the elements of first matrix\n"); for ( c = 0 ; c < m ; c++ ) for ( d = 0 ; d < n ; d++ ) scanf("%d", &first[c][d]); printf("Enter the elements of second matrix\n"); for ( c = 0 ; c < m ; c++ ) for ( d = 0 ; d < n ; d++ ) scanf("%d", &second[c][d]); for ( c = 0 ; c < m ; c++ ) for ( d = 0 ; d < n ; d++ ) sum[c][d] = first[c][d] + second[c][d]; printf("Sum of entered matrices:-\n"); for ( c = 0 ; c < m ; c++ ) { for ( d = 0 ; d < n ; d++ ) printf("%d\t", sum[c][d]); printf("\n"); } return 0;
}

30. Subtract matricesC code to subtract matrices of any order. This program finds difference between corresponding elements of two matrices and then print the resultant matrix.
#include <stdio.h> int main()
{
int m, n, c, d, first[10][10], second[10][10], difference[10][10]; printf("Enter the number of rows and columns of matrix\n"); scanf("%d%d", &m, &n); printf("Enter the elements of first matrix\n"); for (c = 0; c < m; c++) for (d = 0 ; d < n; d++) scanf("%d", &first[c][d]); printf("Enter the elements of second matrix\n"); for (c = 0; c < m; c++) for (d = 0; d < n; d++) scanf("%d", &second[c][d]); for (c = 0; c < m; c++) for (d = 0; d < n; d++) difference[c][d] = first[c][d] - second[c][d]; printf("difference of entered matrices:-\n"); for (c = 0; c < m; c++) { for (d = 0; d < n; d++) printf("%d\t",difference[c][d]); printf("\n"); } return 0;
}

31. C program to transpose a matrixThis c program prints transpose of a matrix. It is obtained by interchanging rows and columns of a matrix. For example if a matrix is1 23 45 6then transpose of above matrix will be1 3 52 4 6When we transpose a matrix then the order of matrix changes, but for a square matrix order remains same.
#include <stdio.h> int main()
{
int m, n, c, d, matrix[10][10], transpose[10][10]; printf("Enter the number of rows and columns of matrix "); scanf("%d%d",&m,&n); printf("Enter the elements of matrix \n"); for( c = 0 ; c < m ; c++ ) { for( d = 0 ; d < n ; d++ ) { scanf("%d",&matrix[c][d]); } } for( c = 0 ; c < m ; c++ ) { for( d = 0 ; d < n ; d++ ) { transpose[d][c] = matrix[c][d]; } } printf("Transpose of entered matrix :-\n"); for( c = 0 ; c < n ; c++ ) { for( d = 0 ; d < m ; d++ ) { printf("%d\t",transpose[c][d]); } printf("\n"); } return 0;
}

32. Matrix multiplication in cMatrix multiplication in c language: c program to multiply matrices (two dimensional array), this program multiplies two matrices which will be entered by the user. Firstly user will enter the order of a matrix. If the entered orders of two matrix is such that they can't be multiplied then an error message is displayed on the screen. You have already studied the logic to multiply them in Mathematics.
#include <stdio.h> int main()
{
int m, n, p, q, c, d, k, sum = 0; int first[10][10], second[10][10], multiply[10][10]; printf("Enter the number of rows and columns of first matrix\n"); scanf("%d%d", &m, &n); printf("Enter the elements of first matrix\n"); for ( c = 0 ; c < m ; c++ ) for ( d = 0 ; d < n ; d++ ) scanf("%d", &first[c][d]); printf("Enter the number of rows and columns of second matrix\n"); scanf("%d%d", &p, &q); if ( n != p ) printf("Matrices with entered orders can't be multiplied with each other.\n"); else { printf("Enter the elements of second matrix\n"); for ( c = 0 ; c < p ; c++ ) for ( d = 0 ; d < q ; d++ ) scanf("%d", &second[c][d]); for ( c = 0 ; c < m ; c++ ) { for ( d = 0 ; d < q ; d++ ) { for ( k = 0 ; k < p ; k++ ) { sum = sum + first[c][k]*second[k][d]; } multiply[c][d] = sum; sum = 0; } } printf("Product of entered matrices:-\n"); for ( c = 0 ; c < m ; c++ ) { for ( d = 0 ; d < q ; d++ ) printf("%d\t", multiply[c][d]); printf("\n"); } } return 0;
}

33. String lengthThis program prints length of string, for example consider the string "c programming" it's length is 13. Null character is not counted when calculating string length. To find string length we use strlen function of string.h.
#include <stdio.h>
#include <string.h> int main()
{
char a[100]; int length; printf("Enter a string to calculate it's length\n"); gets(a); length = strlen(a); printf("Length of entered string is = %d\n",length); return 0;
}

34. c program to compare two stringThis c program compares two strings using strcmp, without strcmp and using pointers. For comparing strings without using library function see another code below.
#include <stdio.h>
#include <string.h> int main()
{
char a[100], b[100]; printf("Enter the first string\n"); gets(a); printf("Enter the second string\n"); gets(b); if( strcmp(a,b) == 0 ) printf("Entered strings are equal.\n"); else printf("Entered strings are not equal.\n"); return 0;
}

35. C program to concatenate stringsThis program concatenates strings, for example if the first string is "c " and second string is "program" then on concatenating these two strings we get the string "c program". To concatenate two strings we use strcat function of string.h, to concatenate without using library function see another code below which uses pointers.
#include <stdio.h>
#include <string.h> int main()
{
char a[100], b[100]; printf("Enter the first string\n"); gets(a); printf("Enter the second string\n"); gets(b); strcat(a,b); printf("String obtained on concatenation is %s\n",a); return 0;
}

36. Reverse stringThis program reverses a string entered by the user. For example if a user enters a string "reverse me" then on reversing the string will be "em esrever". We show you three different methods to reverse string the first one uses strrev library function of string.h header file and in second we make our own function to reverse string using pointers, reverse string using recursion and Reverse words in string. If you are using first method then you must include string.h in your program.
#include <stdio.h>
#include <string.h> int main()
{
char arr[100]; printf("Enter a string to reverse\n"); gets(arr); strrev(arr); printf("Reverse of entered string is \n%s\n",arr); return 0;
}

37. remove vowels string cRemove vowels string c: c program to remove or delete vowels from a string, if the input string is "c programming" then output will be "c prgrmmng". In the program we create a new string and process entered string character by character, and if a vowel is found it is not added to new string otherwise the character is added to new string, after the string ends we copy the new string into original string. Finally we obtain a string without any vowels.
#include <stdio.h>
#include <string.h> int check_vowel(char); int main()
{
char s[100], t[100]; int i, j = 0; printf("Enter a string to delete vowels\n"); gets(s); for(i = 0; s[i] != '\0'; i++) { if(check_vowel(s[i]) == 0) { //not a vowel t[j] = s[i]; j++; } } t[j] = '\0'; strcpy(s, t); //We are changing initial string printf("String after deleting vowels: %s\n", s); return 0;
}

int check_vowel(char c)
{
switch(c) { case 'a': case 'A': case 'e': case 'E': case 'i': case 'I': case 'o': case 'O': case 'u': case 'U': return 1; default: return 0; }
}

38. C program to sort a string in alphabetic orderC program to sort a string in alphabetic order: For example if user will enter a string "programming" then output will be "aggimmnoprr" or output string will contain characters in alphabetical order.
#include <stdio.h>
#include <stdlib.h>
#include <string.h> void sort_string(char*); int main()
{
char string[100]; printf("Enter some text\n"); gets(string); sort_string(string); printf("%s\n", string); return 0;
}

void sort_string(char *s)
{
int c, d = 0, length; char *pointer, *result, ch; length = strlen(s); result = (char*)malloc(length+1); pointer = s; for ( ch = 'a' ; ch <= 'z' ; ch++ ) { for ( c = 0 ; c < length ; c++ ) { if ( *pointer == ch ) { *(result+d) = *pointer; d++; } pointer++; } pointer = s; } *(result+d) = '\0'; strcpy(s, result); free(result);
}

39. C program remove spaces, blanks from a stringC code to remove spaces or excess blanks from a string, For example consider the string
"c programming"
There are two spaces in this string, so our program will print a string"c programming". It will remove spaces when they occur more than one time consecutively in string anywhere.
C programming code#include <stdio.h> int main()
{
char text[100], blank[100]; int c = 0, d = 0; printf("Enter some text\n"); gets(text); while (text[c] != '\0') { if (!(text[c] == ' ' && text[c+1] == ' ')) { blank[d] = text[c]; d++; } c++; } blank[d] = '\0'; printf("Text after removing blanks\n%s\n", blank); return 0;
}

40. C program to swap two stringsC program to swap strings i.e. contents of two strings are interchanged.
#include <stdio.h>
#include <string.h>
#include <malloc.h> int main()
{
char first[100], second[100], *temp; printf("Enter the first string\n"); gets(first); printf("Enter the second string\n"); gets(second); printf("\nBefore Swapping\n"); printf("First string: %s\n",first); printf("Second string: %s\n\n",second); temp = (char*)malloc(100); strcpy(temp,first); strcpy(first,second); strcpy(second,temp); printf("After Swapping\n"); printf("First string: %s\n",first); printf("Second string: %s\n",second); return 0;
}

41. C program to find frequency of characters in a stringThis program computes frequency of characters in a string i.e. which character is present how many times in a string. For example in the string "code" each of the character 'c', 'o', 'd', and 'e' has occurred one time. Only lower case alphabets are considered, other characters (uppercase and special characters) are ignored. You can easily modify this program to handle uppercase and special symbols.
#include <stdio.h>
#include <string.h> int main()
{
char string[100]; int c = 0, count[26] = {0}; printf("Enter a string\n"); gets(string); while ( string[c] != '\0' ) { /* Considering characters from 'a' to 'z' only */ if ( string[c] >= 'a' && string[c] <= 'z' ) count[string[c]-'a']++; c++; } for ( c = 0 ; c < 26 ; c++ ) { if( count[c] != 0 ) printf("%c occurs %d times in the entered string.\n",c+'a',count[c]); } return 0;
}
Explanation of "count[string[c]-'a']++", suppose input string begins with 'a' so c is 0 initially and string[0] = 'a' and string[0]-'a' = 0 and we increment count[0] i.e. a has occurred one time and repeat this till complete string is scanned.

42. Anagram in cAnagram in c: c program to check whether two strings are anagrams or not, string is assumed to consist of alphabets only. Two words are said to be anagrams of each other if the letters from one word can be rearranged to form the other word. From the above definition it is clear that two strings are anagrams if all characters in both strings occur same number of times. For example "abc" and "cab" are anagram strings, here every character 'a', 'b' and 'c' occur only one time in both strings. Our algorithm tries to find how many times characters appear in the strings and then comparing their corresponding counts.
#include <stdio.h> int check_anagram(char [], char []); int main()
{
char a[100], b[100]; int flag; printf("Enter first string\n"); gets(a); printf("Enter second string\n"); gets(b); flag = check_anagram(a, b); if (flag == 1) printf("\"%s\" and \"%s\" are anagrams.\n", a, b); else printf("\"%s\" and \"%s\" are not anagrams.\n", a, b); return 0;
}

int check_anagram(char a[], char b[])
{
int first[26] = {0}, second[26] = {0}, c = 0; while (a[c] != '\0') { first[a[c]-'a']++; c++; } c = 0; while (b[c] != '\0') { second[b[c]-'a']++; c++; } for (c = 0; c < 26; c++) { if (first[c] != second[c]) return 0; } return 1;
}

43. C program to read a fileC program to read a file: This program reads a file entered by the user and displays its contents on the screen, fopen function is used to open a file it returns a pointer to structure FILE. FILE is a predefined structure in stdio.h . If the file is successfully opened then fopen returns a pointer to file and if it is unable to open a file then it returns NULL. fgetc function returns a character which is read from the file and fclose function closes the file. Opening a file means we bring file from disk to ram to perform operations on it. The file must be present in the directory in which the executable file of this code sis present.
#include <stdio.h>
#include <stdlib.h> int main()
{
char ch, file_name[25]; FILE *fp; printf("Enter the name of file you wish to see\n"); gets(file_name); fp = fopen(file_name,"r"); // read mode if( fp == NULL ) { perror("Error while opening the file.\n"); exit(EXIT_FAILURE); } printf("The contents of %s file are :\n", file_name); while( ( ch = fgetc(fp) ) != EOF ) printf("%c",ch); fclose(fp); return 0;
}

44. C program to copy filesC program to copy files: This program copies a file, firstly you will specify the file to copy and then you will enter the name of target file, You will have to mention the extension of file also. We will open the file that we wish to copy in read mode and target file in write mode.
#include <stdio.h>
#include <stdlib.h> int main()
{
char ch, source_file[20], target_file[20]; FILE *source, *target; printf("Enter name of file to copy\n"); gets(source_file); source = fopen(source_file, "r"); if( source == NULL ) { printf("Press any key to exit...\n"); exit(EXIT_FAILURE); } printf("Enter name of target file\n"); gets(target_file); target = fopen(target_file, "w"); if( target == NULL ) { fclose(source); printf("Press any key to exit...\n"); exit(EXIT_FAILURE); } while( ( ch = fgetc(source) ) != EOF ) fputc(ch, target); printf("File copied successfully.\n"); fclose(source); fclose(target); return 0;
}

45. C program to merge two filesThis c program merges two files and stores their contents in another file. The files which are to be merged are opened in read mode and the file which contains content of both the files is opened in write mode. To merge two files first we open a file and read it character by character and store the read contents in another file then we read the contents of another file and store it in file, we read two files until EOF (end of file) is reached.
#include <stdio.h>
#include <stdlib.h> int main()
{
FILE *fs1, *fs2, *ft; char ch, file1[20], file2[20], file3[20]; printf("Enter name of first file\n"); gets(file1); printf("Enter name of second file\n"); gets(file2); printf("Enter name of file which will store contents of two files\n"); gets(file3); fs1 = fopen(file1,"r"); fs2 = fopen(file2,"r"); if( fs1 == NULL || fs2 == NULL ) { perror("Error "); printf("Press any key to exit...\n"); getch(); exit(EXIT_FAILURE); } ft = fopen(file3,"w"); if( ft == NULL ) { perror("Error "); printf("Press any key to exit...\n"); exit(EXIT_FAILURE); } while( ( ch = fgetc(fs1) ) != EOF ) fputc(ch,ft); while( ( ch = fgetc(fs2) ) != EOF ) fputc(ch,ft); printf("Two files were merged into %s file successfully.\n",file3); fclose(fs1); fclose(fs2); fclose(ft); return 0;
}

46. c program to delete a fileThis c program deletes a file which is entered by the user, the file to be deleted should be present in the directory in which the executable file of this program is present. Extension of the file should also be entered, remove macro is used to delete the file. If there is an error in deleting the file then an error will be displayed using perror function.
#include<stdio.h>

main()
{
int status; char file_name[25]; printf("Enter the name of file you wish to delete\n"); gets(file_name); status = remove(file_name); if( status == 0 ) printf("%s file deleted successfully.\n",file_name); else { printf("Unable to delete the file\n"); perror("Error"); } return 0;
}

47. C program to add two complex numbersC program to add two complex numbers: this program calculate the sum of two complex numbers which will be entered by the user and then prints it. User will have to enter the real and imaginary parts of two complex numbers. In our program we will add real parts and imaginary parts of complex numbers and prints the complex number, i is the symbol used for iota. For example if user entered two complex numbers as (1 + 2i) and (4 + 6 i) then output of program will be (5+8i). A structure is used to store complex number.
#include <stdio.h> struct complex
{
int real, img;
};

int main()
{
struct complex a, b, c; printf("Enter a and b where a + ib is the first complex number.\n"); printf("a = "); scanf("%d", &a.real); printf("b = "); scanf("%d", &a.img); printf("Enter c and d where c + id is the second complex number.\n"); printf("c = "); scanf("%d", &b.real); printf("d = "); scanf("%d", &b.img); c.real = a.real + b.real; c.img = a.img + b.img; if ( c.img >= 0 ) printf("Sum of two complex numbers = %d + %di\n",c.real,c.img); else printf("Sum of two complex numbers = %d %di\n",c.real,c.img); return 0;
}