do-while loop

Executes a statement repeatedly, until the value of expression becomes false. The test takes place after each iteration.

Syntax

Explanation

statement is always executed at least once, even if expression always yields false. If it should not execute in this case, a while or for loop may be used.

If the execution of the loop needs to be terminated at some point, a break statement can be used as terminating statement.

If the execution of the loop needs to be continued at the end of the loop body, a continue statement can be used as shortcut.

Notes

As part of the C++ forward progress guarantee, the behavior is undefined if a loop that has no observable behavior (does not make calls to I/O functions, access volatile objects, or perform atomic or synchronization operations) does not terminate. Compilers are permitted to remove such loops.

Keywords

do, while

Example

#include <iostream>
#include <algorithm>
#include <string>
 
int main()
{
    int j = 2;
    do { // compound statement is the loop body
        j += 2;
        std::cout << j << " ";
    } while (j < 9);
    std::cout << '\n';
    // common situation where do-while loop is used
    std::string s = "aba";
    std::sort(s.begin(), s.end());
    do std::cout << s << '\n'; // expression statement is the loop body
    while(std::next_permutation(s.begin(), s.end()));
}

4 6 8 10
aab
aba
baa

See also