In this tutorial, We will discuss While loop in C programming language.
Typically, in programming languages, looping statements are used to perform repetitive statements until a specific condition is met in a block of code.
C program having three basic looping statements
Here, we will learn about while loop in C.
Syntax
while(Test_expression){
//statement(s);
} While loop in C programming language is used to execute a block of statements repeatedly until a given condition returns false. It is similar to for loop in C.
Initially, The initialization statements execute only once. text expression is evaluated by while loop. If the test expression is true(Boolean expression makes only two output 1 or 0) flow of control enters inside the body to execute the code. Continuously, test expression is evaluated and executed until the test expression is false.
This process repeats until the test expression is false.
When the test expression is false. while loop stops the execution and flow of control immediately exits from the loop.
Example
program 1
Here, it is a simple example to display 1 to 10
#include <stdio.h>
#include <stdlib.h>
int main()
{
int a=1;//variable declaration
//and initialization
while(a<=10){//test expression
printf("value of a :%d\n",a);
//display statements
a++;//increment statements
}
getch();
return 0;
}
When the above code is compiled and executed, it produces the following result
value of a :1 value of a :2 value of a :3 value of a :4 value of a :5 value of a :6 value of a :7 value of a :8 value of a :9 value of a :10
the above program displays the positive numbers from 1 to 10 using while loop
Program 2
#include <stdio.h>
#include <stdlib.h>
int main()
{
int i=1;
while(i<=10){
printf("%d\n",i*i);
i++;
}
getch();
return 0;
}
When the above code is compiled and executed, it produces the following result:
Square number of between 1 to 100 1 4 9 16 25 36 49 64 81 100 End the program
The above program displays square numbers between 1 to 100 using while loop
Program 3
Find factorial using while loop in C language
#include <stdio.h>
#include <stdlib.h>
int main()
{
int num;
long fact;
printf("Enter the number for find factorials :");
scanf("%d",&num);
fact=1;
while(num>0) //if num>0, loop is terminated
{
fact*=num; //factorial=factorial*number
--num;
}
printf("Factorial is := %ld", fact);
getch();
return 0;
} When the above code is compiled and executed, it produces the following result:
Enter the number for find factorials: 6
Factorial is: 720
the above program calculates factorial of given numbers using the while loop
while(true){ //it is always true
printf("This loop would never end");
} Program 1
#include <stdio.h>
#include <stdlib.h>
int main()
{
int i=5;
while(i>=5){ //i value greater than initialized value
printf("%d",i);
i++;
}
return 0;
} When the above code is compiled and executed, it produces the following result:
This loop would never end
While loop with an array in C language
#include <stdio.h>
#include <stdlib.h>
int main()
{
int arr[]={45,67,75,34,65,89};
int i=0;
while(i<=5){
printf("%d\n",arr[i]);
i++;
}
getch();
return 0;
} When the above code is compiled and executed, it produces the following result:
45 67 75 34 65 89
the above program displays elements of the array using the while loop
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Java While keyword
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