while loop

Conditionally executes a statement repeatedly.

# Notes

Regardless of whether statement is a compound statement, it always introduces a block scope. Variables declared in it are only visible in the loop body, in other words,

is the same as

As part of the C++ forward progress guarantee, the behavior is undefined if a loopthat is not a trivial infinite loop(since C++26) without observable behavior does not terminate. Compilers are permitted to remove such loops.

# Example

#include <iostream>
 
int main()
{
    // while loop with a single statement
    int i = 0;
    while (i < 10)
         i++;
    std::cout << i << '\n';
 
    // while loop with a compound statement
    int j = 2;
    while (j < 9)
    {
        std::cout << j << ' ';
        j += 2;
    }
    std::cout << '\n';
 
    // while loop with a declaration condition
    char cstr[] = "Hello";
    int k = 0;
    while (char c = cstr[k++])
        std::cout << c;
    std::cout << '\n';
}

# See also

C documentation