How does a do-while loop work in the c programming language?

 How does a do-while loop work in the c programming language?

We use control statements in programming languages to execute code based on certain conditions. In C programming the concept of control statement is the same. These control statements iterate pieces of code multiple times according to user requirements. These iterations are controlled by some conditions that are given by the programmer or the developer. There are mainly three types of control statements or looping statements, which are,

1) do-while loop

2) while loop

3) for loop

Today our main focus is on the do-while loop. We are going to look at the do-while loop and the basic syntax of the do-while loop. After that, we are going to look at an example to get a better understanding of do-while loop and its working. These loop statements increase the performance of the code.

Below is the syntax of the do-while loop

do{

//Write the coding part here

}while(condition);

Note a very important point about the do-while loop, remember that the do-while will run at least once whether the condition is true or false it is going to run at least one time. The do-while loop starts with the do keyword. After the do keyword, the coding block comes, and at last, the end of the loop a while condition part is used in which some condition is given and this condition ends with a semicolon. If the condition is true then the do-while loop runs again. And if the condition is false then the loop terminates.

Now we are going to look at a simple example for a user to enter a password. The loop will keep iterating and repeat until the user enters the correct password. On entering the correct password the while condition will become false and the do-while loop will terminate. Let us look at the example given below.

 

At the start of the code, we used two header files <stdio.h> and <string.h>. The <stdio.h> file deals with standard input and output functions like print() and scanf(). And <string.h> deals with string functions like strcmp().

We declared a char array variable named it as password and assigned it a value "secret" After that we took another variable named as input[20] with an array size of 20.

In the do-while loop, we prompt the user to enter the password in the input[20] variable. In the do-while loop, we used the condition that will check whether the given value is correct or not.

We used strcmp() function and used it like this strcmp(input, password) the strcmp() returns 0(zero) when the two compared strings are equal which are input and password, and returns non-zero when strings are not equal.

When two strings are equal it will return 0. The do-while loop will terminate, and access will be granted to the user for a valid password.

Congratulations we have successfully implemented the do-while loop with an example.