Which of the following loops is guaranteed to execute at least once?

Question

Problem :

I am very new to programming world. According to my senior a for loop will always get executed at least once even if a required condition is not met.

Please find below example for your reference:

for (int i=6; i <=5; i++) {
    //inappropriate for this question
}

According to my senior above listed loop will be executed at least once but it does not or let me know if I am I missing something?

Answer 1

I can help you in understanding this concept. I can say that the for loop is always evaluated at least once.
But if a for loops condition is not met because of some reason then its block will never be executed. Any loop will only get executed if its condition is true. As far as the for loop and the while loop are considered then I can certainly say that both will check a condition before a body is executed and they will never get executed if a condition is false.

The only loop that will always get executed is the do while loop. As far as the do while loop is considered then the condition is not evaluated until you reach the end of a loop. Because of this nature of it a do while loop will always get executed at least once.

Hope it helps.

 

 

Answer 2

The do-while loop is similar to a while loop. The only difference is that the condition occurs at the end of the loop. Having the loop condition at the end of the loop gives the guarantees that the body of the loop always executes at least once.

Test condition:

The test condition must be enclosed in parentheses and followed by a semicolon. Semicolons are also placed at the end of each statement within the blocks. The body of the loop is enclosed in curly braces to indicate the body of the loop. This method also helps to increase the readability of code.

Exit condition loop:

The do-while loop is an exit-condition loop that means the body of the loop will always be executed first. After that, the test condition is evaluated. If the test condition is true the body of the loop is executed. If the loop condition is false, the loop terminates and the program execution continues with the statement following while.

Example:

char ans;

do

{

      cout<< "Do you want to continue (Y/N)?\n";

      cout<< "You must type a 'Y' or an 'N'.\n";

      cin >> ans;

}

while((ans !='Y')&&(ans !='N')&&(ans !='y')&&(ans !='n'));