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What is the difference between Entry Controlled and Exit Controlled loop in C?
Learn: What is Entry Controlled and Exit Controlled loops in C/C++ programming language, what are the differences between them?
Entry and Exit Controlled Loop in C
Loops are the technique to repeat set of statements until given condition is true. C programming language has three types of loops - 1) while loop, 2) do while loop and 3) for loop.
These loops controlled either at entry level or at exit level hence loops can be controlled two ways
- Entry Controlled Loop
- Exit Controlled Loop
Entry Controlled Loop
Loop, where test condition is checked before entering the loop body, known as Entry Controlled Loop.
Example: while loop, for loop
Exit Controlled Loop
Loop, where test condition is checked after executing the loop body, known as Exit Controlled Loop.
Example: do while loop
Consider the code snippets
Using while loop
int count=100;
while(count<50)
printf("%d",count++);
Using for loop
int count;
for(count=100; count<50; count++)
printf("%d",count);
In both code snippets value of count is 100 and condition is count<50, which will check first, hence there is no output.
Using do while loop
int count=100;
do
{
printf("%d",count++);
}while(count<50);
In this code snippet value of count is 100 and test condition is count<50 which is false yet loop body will be executed first then condition will be checked after that. Hence output of this program will be 100.
Differences Table
Entry Controlled Loop |
Exit Controlled Loop |
Test condition is checked first, and then loop body will be executed. |
Loop body will be executed first, and then condition is checked. |
If Test condition is false, loop body will not be executed. |
If Test condition is false, loop body will be executed once. |
for loop and while loop are the examples of Entry Controlled Loop. |
do while loop is the example of Exit controlled loop. |
Entry Controlled Loops are used when checking of test condition is mandatory before executing loop body. |
Exit Controlled Loop is used when checking of test condition is mandatory after executing the loop body. |
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