C break

Summary: in this tutorial, you will learn how to use the C break statement to exit a loop, including for loop, while loop, and do...while loop.

Introduction to the C break statement

The break statement allows you to exit a loop early than usual. Typically, you’ll use the break statement in a for loop, while loop, or do...while loop.

The break statement includes the break keyword followed by a semiconlon (;) like this:

break;
Code language: C++ (cpp)

In practice, you often use the break statement with an if statement to specify the condition to exit the loop. It’ll look like this:

// somewhere inside a loop
if(expression)
    break;
Code language: C++ (cpp)

In this syntax, if the expression is non-zero (or true), the break statement will exit the loop.

Note that you can use the break statement inside a case statement of the switch...case statement. However, this tutorial focuses on how to use the break statement inside a loop.

Using C break statement in a for loop

The following example illustrates how to use the break statement inside a for loop:

#include <stdio.h>

int main()
{
    int i;
    for (i = 0; i < 10; i++)
    {
        if (i == 5)
            break;

        printf("%d ", i);
    }
}
Code language: C++ (cpp)

Output:

0 1 2 3 4

The for loop is supposed to execute 10 times. However, when i reaches 5, the break statement immediately terminates the loop. Therefore, the loop runs only 5 times.

Using C break statement in a do…while loop

The following example shows how to use the break statement inside a do...while loop:

#include <stdio.h>

int main()
{
    char key;

    printf("Type something (q to quit): ");

    do
    {
        scanf("%c", &key);

        if (key == 'Q' || key == 'q')
            break;

    } while (1);
}
Code language: C++ (cpp)

How it works.

The condition in the do…while loop is 1. Therefore, the do...while loop will execute repeatedly until it encouters a break statement.

The program prompts for a character:

scanf("%c", &key);
Code language: C++ (cpp)

If you type the letter q or Q, the break statement will terminate the loop immediately:

if (key == 'Q' || key == 'q')
    break;
Code language: C++ (cpp)

Using C break statement in a while loop

The following example illustrates how to use the break statement inside a while loop:

#include <stdio.h>

int main()
{
    int n, total = 0;

    printf("Enter a positive number (0 or negative to exit):");

    while (1)
    {
        scanf("%d", &n);
        if (n <= 0)
            break;

        total += n;
    }
    printf("The total is %d", total);
}
Code language: C++ (cpp)

How it works.

Like the above example, the while(1) will run its body until it encounters a break statement.

Inside the loop, prompt users for a positive integer:

 scanf("%d", &n);
Code language: C++ (cpp)

If the input number is less than or equal to zero, the break statement ends the loop:

if (n <= 0)
    break;
Code language: C++ (cpp)

However, if the input number is greater than zero, the program adds it to the total:

total += n;
Code language: C++ (cpp)

Once the while loop ends, show the total of entered numbers:

printf("The total is %d", total);
Code language: C++ (cpp)

Summary

• Use the C break statement to exit a loop including for, while, and do...while loop.