std::source_location in C++ 20

The latest C++ standard version 20, brought about a fresh header file called <source_location> Header. It has an efficient method of obtaining details of a function or expression's source location while running. This functionality is immensely beneficial for debugging and profiling activities that help developers locate errors and performance problems more quickly.

std::source_location Class

The <source_location> header provides a new class called std::source_location, which has the following member functions:

• file_name(): The function or expression's defined source file name can be obtained in the form of a std::string object upon return.
• line(): An integer that is not signed, which includes the number of the source file line where the expression or function has been defined, is returned.
• column(): The function or expression's defined column number in the source file is included in an unsigned int return value.
• function_name(): The std::source_location object's origin function name is returned in a std::string object.
• current(): It is a static member function that is used to create a source location object of the place where it is called in the program.

Syntax

std::source_location src = source_location_objects;

Examples of Source Location

Example 1: Program to illustrate the use of std::source_location

// C++ Program to demonstrate use of source_loaction to
// print function details
#include <iostream>
#include <source_location>
using namespace std;

// function for which we check source location
void foo()
{
    // declaring source location object for current source
    source_location src = source_location::current();

    // printing details
    cout << "Function: " << src.function_name() << '/n';
    cout << "File: " << src.file_name() << "\n";
    cout << "Line: " << src.line() << "\n";
    cout << "Column: " << src.column() << "\n";
}

// driver code
int main()
{
    foo();
    return 0;
}

Output

Function: void foo()
File: main.cpp
Line: 11
Column: 51

Example 2: Program to illustrate the use of source location for log messages.

// C++ program to log messages with source location using
// source_location header
#include <iostream>
#include <source_location>

void log(std::string_view message,
         const std::source_location& location
         = std::source_location::current())
{
    std::cout << location.file_name() << ":"
              << location.line() << " ("
              << location.function_name() << "): " << message
              << "\n";
}

void foo() { log("Hello, world!"); }

int main()
{
    foo();
    return 0;
}

Output

main.cpp:9 (void foo()) Hello, world!

Advantages of using <source_location> Header

Advantages of using <source_location> header mentioned below:

• Easier debugging: Developers can efficiently locate the origin of a function or code with the aid of the source_location class, which offers insights such as filename, line number, column number, and function name. This data can be beneficial when dealing with obscure errors or debugging intricate code.
• Improved logging: Incorporating the source_location class into the code provides developers with elaborate logging details that pinpoint the exact location where a log message originated. This feature enables faster identification of the issue at hand, making troubleshooting more effective.
• Better profiling: Developers can use the source_location class to pinpoint the location of a function's call, revealing potential performance bottlenecks. With this information, they can optimize their code, leading to improved application performance.