Let us implement Do while loop in C programming and understand how a while loop works in C programming with its algorithm, flowchart, example and explanation.
A Do while loop is a control flow statement that helps to repeatedly iterate a set of code based on a given Boolean condition. The do while loop can be thought of as a repeating if – else statement.
Do While Loop Flowchart
This looping construct follows an exit condition system wherein the condition is tested after the program control moves into the inner blocks of code within the do while block.
A Do while loop, therefore, verifies the condition after every iteration of the loop body, and hence, it executes the iteration at least once even if the condition is false.
Do While Loop Syntax
1 2 3 4 5 | do { sequence of statements; increment / decrement; }while(condition); |
The program control first executes the set of instructions within the do while block and then it validates the condition.
If the condition evaluates to true, then the set of instructions within the do while loop are executed again.
This execution of do while block is re-iterated until the condition evaluates to false. Once, the condition becomes false, the program control exits out of the do while loop and executes the other statements if any.
There is a difference between while and do while loop in C programming which you must know to understand the looping structures.
Do While Loop Algorithm
1 2 3 | DO Sequence WHILE test-condition |
For a do while condition to change at every iteration, it is mandatory to provide a statement within the while loop which changes the condition variables in the while loop.
For this purpose, we usually use an increment or a decrement operator within these looping constructs. Otherwise, it becomes an infinite loop.
Note: The C program of Do while loop is compiled with GNU GCC compiler using CodeLite IDE on Microsoft Windows 10 operating system.
C Program To Print Numbers using Do While Loop
1 2 3 4 5 6 7 8 9 10 11 12 13 14 | #include<stdio.h> int main() { int count = 0, limit; printf("Enter the limit:\t"); scanf("%d", &limit); do { printf("%d\t", count); count = count + 1; }while(count < limit) return 0; } |
To find more implementations of Do while in C programming, you must check this list of C programs.
Output
In order to summarize program flow of a Do while loop in C programming, here are the steps:
- Initialization
- Execution of block statements
- Condition Validation
- Increment/Decrement
Nested Do while Loop
A nested do while loop is useful in many scenarios such as pattern programming, multi-dimensional arrays and much more. Let us see an example of a nested do while loop in C programming.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 | #include<stdio.h> int main() { int i = 0, j; do { printf("%d\t", i); j = i + 1; do { printf("%d\t", j); j++; }while(j < 5); printf("\n"); i = i + 1; }while(i < 5); return 0; } |
The first do while loop is the outer do while loop and the second do while statement is known as the inner loop.
If you have any compilation errors or doubts about Do while loop in C programming, let us discuss in the comment section below. Find more about the Do while loop on Wikipedia.