TR
PT1420
5/13/14
Unit Assignment 4

l. What is the general fom1at of the statement used to code decisions in an application? A power full asset of the computer is its ability to make decisions and to take alternate course of action based on the outcome.
2. What is a Boolean expression? a logical statement that is either TRUE or FALSE.
3 . Explain the purpose of comparison operators and logical operators. The purpose of a comparison operator is to test some kind of relationship between two entities examples are >, <, ==, !=, etc
4. How does a comparison performed on numeric data differ from a comparison performed on string data? There are commonly used interchangeably, and the distinction between them is a small one. Comparison to" should be used when comparison is made between specific people, things, or other instances.
5. How does Visual Basic compare the Text property of a text box? When you compare the Text property of a text box with another value the Text property behaves like a variant. Visual Basic compares one text box to another as strings and compares a text box to a numeric variable or constant with a numeric compare. You can force a numeric comparison on a Text property by using the Val function.
6 . Why would it be useful to include the ToUpper method in a comparison? When comparing strings, the case of the characters is important. An uppercase “Y” does not compare equal to a lowercase “y”. Since the user may type a name or word in either uppercase or lowercase or a combination of the two, we must check all possibilities. The easiest way is to use the string function Ucase or Lcase, which returns the uppercase or lowercase equivalency of a string, respectively.
7. Name the types of items that can be used in a comparison. The conditions to be tested can be formed with numeric variables and constants, string variables and constants, object properties, and arithmetic expressions. However, it is important to note that comparisons must be made on “like types”; that is, strings can be compared only to other strings, and numeric values can be compared only to other numeric values, whether a variable, constant, property, or arithmetic expression.
8. Explain a Boolean variable test for True and False. Give an example. Visual Basic evaluates the condition in an If statement. If the condition is a Boolean variable name, it holds the values True or False.
For example: If blnSuccessfulOperation = True Then is equivalent to If blnSuccessfulOperation Then…
Boolean variables hold the value zero when False, and negative one when True.
9 . Give an example of a situation where nested Ifs would be appropriate. An example where nested Ifs would be appropriate would be a situation where multiple conditions must be tested and input validation required. The following code would be extremely awkward if block ifs were used instead. intHours = Val(txtHours.Text) intPayRate = Val(txtPayRate.Text) If intHours > 0 And intHours <= 40 Then If intPayRate > 0 Then cPay = intHours * intPayRate Else MsgBox “Please Input the Rate of Pay” End If Else MsgBox “Please enter the number of non-overtime hours worked this week.” EndIf
10 . Define the term validation. \'(' hen is it appropriate to do validation? A message box would be used whenever a message must be displayed to the user. Validating input data is an appropriate time to use a message box. If we reject bad data, we need to let the user know why the desired action was not achieved l l. Define the term checking a range. Button/Icon Constant
OK button OKOnly
Critical Message icon Critical
Warning Query icon Question
Warning Message icon Exclamation
Information Message icon Information
12. When would it be appropriate to use a Case structure? Give an example. Case statements are used when a single variable is tested for multiple values. Any decisions that can be coded as a Case structure can also be coded with a nested if statements. But a Case structure is usually easier to write and understand than a complex nested if statement.
13. Explain the difference between Step Into and Step Over. Step Into : Step Into is used for debugging the test steps line by line. When the procedure gets called, Step Into enables you to get inside the procedure and debugs the procedure steps line by line. Step Over: Step Over will enable, only after the debugging is started with Step Into / Run From Step / Run to Step. Step Over is used for debugging the test steps line by line, but when the procedure is called, the entire procedure call will be executed as single step. The cursor never gets inside the procedure. Step Out : Step Out will enable, only after the debugging cursor gets inside a procedure. The cursor will get inside a procedure only when the test is debugged with Step Into.
14. What steps are necessary to view tJ1e current contents of a va1iable during program execution? The steps for viewing the contents of a variable during run time are
1. Break the execution (using the Run menu, the toolbar button, or a breakpoint).
2. Click on the View Code button in the Project Explorer window or select Code from the View menu.
3. Point to the variable or expression you wish to view.
The current contents of the expression will pop up in a label.