How to Run a C++ Program Without Namespace?

C++ allows us to use standard library features without declaring using namespace std;. We can access these features by qualifying their names with the std:: prefix.

• std:: specifies that a name belongs to the standard namespace.
• It helps avoid naming conflicts with other identifiers.

Example:

Instead of writing: cout << "GeeksforGeeks";
we can write: std::cout << "GeeksforGeeks";

Approach

The approach is to remove using namespace std; and explicitly qualify standard library names with std::.

• Include the required standard library header.
• Remove the using namespace std; statement.
• Add std:: before standard library names such as cout and endl.

Example: The following program prints a message without using using namespace std;.

#include <iostream>
#include <string>

int main()
{

    std::cout << "geeksforgeeks";
    return 0;
}

geeksforgeeks

Example: The std:: prefix can also be used with standard library functions and objects when needed.

#include <bits/stdc++.h>

int main()
{

    int a = 5;
    int b = 10;
    int c = a + b;
    std::cout << c << std::endl;
    return 0;
}