C++ ostream

The C++ ostream class provides a set of functions and operators for writing data as output.

Before using ostream, we need to include the <iostream> header in our program.

#include <iostream>

C++ Insertion Operator <<

To write data to the console using ostream, we can use the cout object with the insertion operator << operator.

#include <iostream>
using namespace std;

int main() {

    int entered_number;

    // write the text "Hello World!" to the screen
    cout << "Hello World!";
    
    return 0;
}

Output

Hello World!

C++ put() Function

The put() function of ostream is primarily used to write characters to the console. For example,

#include <iostream>
using namespace std;

int main() {

    char ch = 'A';

    // print a character to the console
    cout.put(ch);
    
    cout<< endl ;

    // print another character to the console
    cout.put('C'); 

    return 0;
}

Output

A
C

C++ write() Function

The write() function of ostream is generally used to write blocks of data into the console. For example,

#include <iostream>
#include <cstring>

using namespace std;

int main() {

    // create a C-string
    const char* str = "Hello, World!";

    // print the C-string
    cout.write(str, strlen(str));
    
    return 0;
}

Output

Hello, World!

Here, we have written a C-string Hello, World to the output stream using the write() function.

Note: We have used a C-string with the write() function because it doesn't work with std::string objects of C++.