Question

what are stream manipulators in C++? write a detail note.

Answer 1

Stream Manipulators are built in functions which are often used in conjunction with the insertion (<<) and extraction (>>) operators on stream objects.

The stream manipulators in C++ are given as:

• endl

This manipulator has the same functionality as ‘\n’(newline character). But this also flushes the output stream.

Example

#include<iostream>
int main() {
   std::cout << "Hello" << std::endl << "World!";
}

Output

Hello
World!

• setprecision

This manipulator changes floating-point precision.

Example

#include <iostream>
#include <iomanip>
int main() {
   const long double pi = 3.141592653589793239;
   std::cout << "default precision (6): " << pi << '\n'
             << "std::setprecision(10): " << std::setprecision(10) << pi << '\n';
}

Output

default precision (6): 3.14159
std::setprecision(10): 3.141592654

• setw

This manipulator changes the width of the next input/output field.

Example

#include <iostream>
#include <iomanip>
int main() {
   std::cout << "no setw:" << 42 << '\n'
             << "setw(6):" << std::setw(6) << 42 << '\n'
             << "setw(6), several elements: " << 89 << std::setw(6) << 12 << 34 << '\n';
}

Output

no setw:42
setw(6):    42
setw(6), several elements: 89    1234