COMP122
Week 1 Homework

Part 1: Complete the following problems.

1. What is machine code? Why is it preferable to write programs in a high level language such as C++? A machine code is consisting of a low level programming language that is executed by CPU. Writing a program in C++, a computer translate the C++ code in the machine code for the CPU to understand.

2. What does a compiler do? What kinds of errors are reported by a compiler?

Compiler help translate high level programming language into machine code. That will report any syntax, type errors, and declaration errors.

3. What does the linker do?

The linker takes in object of a library file which combines them into an module or load module. It can also converts object files into executable files.

4. What is an algorithm?

An algorithm is a set of instructions to follow when writing any kind of programs.

5. Bob enters a pizza shop and notices there are three different sizes of pizzas available. Sizes are given as the diameter of the pizza in inches. The cost of a pizza is based on the size. Bob would like to know which size of pizza has the lowest cost per square inch.

a. Identify the inputs and outputs for this problem.

The inputs are the diameter of each pizza and cost.
The outputs are the prompt for the users to determine the diameter and cost of each pizza which he will finished the cost of per square inch.

b. Identify the processing needed to convert the inputs to the outputs. Enter the diameter of the pizza which area of circle = (Pi(r )^2) / cost of pizza = cost per square inch

c. Design an algorithm in pseudocode to solve this problem. Make sure to include steps to get each input and generate each output. //Constants Area= Pi (r)^2

//Variables Diameter Cost

//Output “Please enter the diameter of the pizza.” “Please enter the cost of the pizza.”

//Calculation Diameter / 2=r Area/cost

//Output “The cost per square inch of your pizza is.”

Part 2: Complete the following problems.

1. Given the following expressions, what value would they have in a C++ program? a. 13 / 4 =3 b. 2 + 12 / 4=5 c. 21 % 5=1 d. 3 - 5 % 7=1 e. 17.0 / 4=4 f. 8 - 5 * 2.0=-2 g. 14 + 5 % 2 – 3=12 h. 15.0 + 3.0 / 2.0=16

2. Given the following variable declarations:

int num1 = 10, num2 = 20, newNum = 30; double x = 5.0, y = 8.0;

Determine which of the following assignment statements are valid. For each invalid statement, explain why it is invalid. Assume that each statement immediately follows the above variable declarations.

a. num1 = 15; invalid, num 1 = 10 b. num2 = num1 - 18; invalid, num 1 = 10 and num 2 = 20 c. num1 = 5; num2 = 2 + 6; num1 = num2 / 3; invalid, num 1 =10, num 2 = 20 d. num1 + num2 = newNum; valid e. x = 12 * num1 - 15.3; invlaid, x=5.0 f. num1 * 2 = newNum; invlaid, newNum=30
g. x / y = x * y; nvalid, dividing and mulltipling the same number do not give the same result h. num2 = num1 % 2.0; invalid, num2=20 i. newNum = static_cast<int> (x) % 5; invalid, newNum=30 j. x = x + 5; invalid, x=5 k. newNum = num1 + static_cast<int> (4.6 / 2); ; invalid, newNum=30

3. For each of the following lines of variable declarations, identify it as valid or describe what makes the line invalid.

Line 1:n = 12; invalid, the data type is not specified
Line 2: char letter = ; invalid, the variable has no value or remove the =
Line 3: int one = 5, two valid
Line 4: double x, y, z; valid

4. Write C++ statements that accomplish each of the following:

a. Declare and initialize int variables x to 25 and y to 18. int x= 25 int y= 18 b. Declare and initialize an int variable temp to 10 and a char variable ch to 'A'.
Int temp= 10
Char ch= A c. Add 5 to the int variable x which already exists. x+5 d. Declare and initialize a double variable payRate to 12.50.
Double pay rate = 12.50 e. Copy the value from an existing int variable firstNum into an existing int variable tempNum. tempNum + first Num f. Swap the contents of existing int variables x and y. (Declare any new variables you need.)
Int x = 1
Int y = 2 g. Output the contents of existing double variables x and y, and also output the value of the expression x + 12 / y - 8.

cout << “ x = “ << x; cout << “ y = “ << y; cout << “ x + 12 / y – 8 = “ << x + 12 / y – 8 << endl;

h. Copy the value of an existing double variable z into an existing int variable x.

5. Given the following variable declarations:

int x = 2, y = 5, z = 6;

What is the output from each of the following statements?

a. cout << "x = " << x << ", y = " << y << ", z = " << z << endl; x = 2, y =5, z = 6 b. cout << "x + y = " << x + y << endl; x + y = 7 c. cout << "Sum of " << x << " and " << z << " is " << x + z << endl;
Sum of 2 and 6 is 8 d. cout << "z / x = " << z / x << endl; z / x = 3 e. cout << "2 times " << x << " = " << 2 * x << endl;
2 times 2 = 4

6. Given the following variable declarations:

int a = 5, b = 6, c;

What is the value of a, b, and c after each of the following statements executes? Assume that the statements execute in the sequence given.

a. a = b++ + 3; 6+3 b. c = 2 * a + ++b; c = 17 c. b = 2 * ++c - a++; 6 = 2 * c + 1- 5