std::source_location:: line

Returns the line number represented by this object.

Parameters

(none)

Return value

The line number represented by this object.

An implementation is encouraged to return 0 when the line number is unknown.

Example

#include <iostream>
#include <string_view>
#include <source_location>
 
inline void cur_line(
    const std::string_view message = "",
    const std::source_location& location = std::source_location::current())
{
    std::cout
        << location.line() // <- the line # of a call site
        << ") "
        << message; 
}
 
int main()
{
    cur_line("++\n");
    cur_line(); std::cout << "Hello,\n";
    cur_line(); std::cout << "C++20!\n";
    cur_line("--\n");
}

17) ++
18) Hello, 
19) C++20! 
20) --

See also