do - while loop

Conditionally executes a statement repeatedly (at least once).

Syntax

Explanation

When control reaches a do statement, its statement will be executed unconditionally.

Every time statement finishes its execution, expression will be evaluated and contextually converted to bool . If the result is true , statement will be executed again.

If the loop needs to be terminated within statement , a break statement can be used as terminating statement.

If the current iteration needs to be terminated within statement , 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 is not a trivial infinite loop (since C++26) without observable behavior does not terminate. Compilers are permitted to remove such loops.

Keywords

do , while

Example

#include <algorithm>
#include <iostream>
#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