Map Elements using for_each Algorithm in C++

This C++ program prints elements of map using for_each algorithm. The for_each function takes three parameters – iterator to the beginning of the container, the iterator to the end of the container and a function or function object of class X. A function object is a programming construct allowing an object to be invoked or called as if it were an ordinary function. The class X has an operator() which allows the for_each to execute the code inside it.

Here is the source code of the C++ program prints elements of map using for_each algorithm. The C++ program is successfully compiled and run on a Linux system. The program output is also shown below.

```
/*
```

 * C++ Program to Print map using for_each algorithm

```
 */ 
```
```
#include <iostream>
```
```
#include <algorithm>
```
```
#include <string>
```
```
#include <map>
```
```
 
```
```
class X {
```
```
    public:
```

        void operator() (std::pair <int, std::string> p){

            std::cout << p.first << "\t" << p.second << std::endl;

```
        }
```
```
};
```
```
 
```
```
int main()  
```
```
{
```
```
    X x;
```
```
    std::map <int, std::string> people;
```

    people.insert(std::pair <int, std::string>(1, "Roger Federer"));

    people.insert(std::pair <int, std::string>(2, "Rafael Nadal"));

    people.insert(std::pair <int, std::string>(3, "Andy Murray"));

    people.insert(std::pair <int, std::string>(4, "Novak Djokovic"));

```
 
```

    std::cout << "Id\tPlayer Name " << std::endl

              << "--\t------------" << std::endl;

    for_each(people.begin(), people.end(), x);

```
    return 0;
```
```
}
```

$ a.out
Id      Player Name
--      ------------
1       Roger Federer
2       Rafael Nadal
3       Andy Murray
4       Novak Djokovic

Sanfoundry Global Education & Learning Series – 1000 C++ Programs.

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