ios manipulators unitbuf() function in C++

The unitbuf() method of stream manipulators in C++ is used to set the unitbuf format flag for the specified str stream. This flag flushes the associated buffer after each operation.

Syntax:

ios_base& unitbuf (ios_base& str)

Parameters: This method accepts str as a parameter which is the stream for which the format flag is affected.

Return Value: This method returns the stream str with unitbuf format flag set.

Example 1:

// C++ code to demonstrate
// the working of unitbuf() function

#include <iostream>
#include <sstream>

using namespace std;

int main()
{

    // Initializing the character
    char a, b, c;

    // Stream input with leading whitespaces
    istringstream iss("GFG");

    // Using unitbuf()
    // buffer flushed 3 times
    iss >> unitbuf >> a >> b >> c;

    cout << "unitbuf flag: "
         << a << endl
         << b << endl
         << c << endl;

    return 0;
}

Output:

unitbuf flag: G
F
G

Example 2:

// C++ code to demonstrate
// the working of unitbuf() function

#include <iostream>
#include <sstream>

using namespace std;

int main()
{

    // Initializing the character
    char a, b, c, d, e;

    // Stream input with leading whitespaces
    istringstream iss("GEEKS");

    // Using unitbuf()
    // buffer flushed 5 times
    iss >> unitbuf >> a >> b >> c >> d >> e;

    cout << "unitbuf flag: "
         << a << endl
         << b << endl
         << c << endl
         << d << endl
         << e << endl;

    return 0;
}

Output:

unitbuf flag: G
E
E
K
S

Reference: http://www.cplusplus.com/reference/ios/unitbuf/