The Shortcomings Of Using Namespace Std In C++

Introduction

You have to learn C++ in many Bachelors in Information Technology program as a part of your college syllabus, usually in second semester. Students are supposed to write all the C++ code in a paper with a pen, the less they write and cross, the more tidy their work becomes, resulting in better marks. So teachers teach students to using namespace std so that they do not forget to use std:: when needed and its less things to write.

If your only purpose of practicing C++ is to pass exam than it is okay to do so. But in real world, this practice is discouraged. Try to compile the following seemingly innocent program:

#include <iostream>
using namespace std;
class data 
{
    int id;
    char* name;
public:
    data(int passed_id, char* passed_name)
    {
        this -> id = passed_id;
        this -> name = passed_name;
    }
};

int main()
{
    data my_record = data(20, "Sujan");
    return 0;
}

It will not compile and you will notice there is some mention of ambiguity. Its because data class is already defined in the std namespace and that causes conflict.

Solution

Always use std:: in front of statements where you use classes from the std namespace. I see alot of professional C++ developers doing it

But wait, there is a better way

You are discouraged from using the entire std namespace in your program, however, you can do this

using std::cout;
using std::cin;
using std::string;
using std::endl;