Chapter 5, Problem 1.1SRE

Fill in the blanks in each of the following statements:

Typically,    statements are used for counter-controlled

iteration and    statements for sentinel-controlled iteration.

Program Description Answer

The “for loop” statements are used for counter-controlled iteration and “while loop” statements used for sentinel-controlled iteration.

Explanation of Solution

“for” loop:

• The for loop gets starts with the keyword “for”. It contains three control structures and these control structures are separated using (;) semicolon. They are:
  • “Initial-action”, used to initialize the control variable.
  • “Loop-continuation-condition”, it determines whether the loop gets repeated.
  • “Action-after-each-iteration”, used to update the control variable for next iteration.
  • So, the “for” loop always used for counter-controlled iteration.

A for loop is used to execute a block of statements repeatedly until the condition is true. The syntax of for loop:

for(i=initial_value;i<end_value;i++)

{

  Loop statements;

}

• Here, the variable “i” is referred as control variable, it controls how many times that the loop gets executed.

“while” loop:

The “while” loop first checks its expression and then the statements inside the loop are executed. It is also called as pretest loops.

• These loops do not have to be terminated with a semicolon.
• With the false expressions, the loops can be terminated.
• So, the “while” loop always used for sentinel-controlled iteration.

Syntax:

The syntax for the while loop is as follows:

//while loop statement

while (condition)

{

    //statement

}