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What are C++ Manipulators (endl, setw, setprecision, setf)?
Stream Manipulators are functions specifically designed to be used in conjunction with the insertion (<<) and extraction (>>) operators on stream objects, for example −
std::cout << std::setw(10);
They are still regular functions and can also be called as any other function using a stream object as an argument, for example −
boolalpha (cout);
Manipulators are used to changing formatting parameters on streams and to insert or extract certain special characters.
Following are some of the most widely used C++ manipulators −
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!
showpoint/noshowpoint
This manipulator controls whether decimal point is always included in the floating-point representation.
Example
#include <iostream>
int main() {
std::cout << "1.0 with showpoint: " << std::showpoint << 1.0 << '\n'
<< "1.0 with noshowpoint: " << std::noshowpoint << 1.0 << '\n';
}Output
1.0 with showpoint: 1.00000 1.0 with noshowpoint: 1
setprecision
This manipulator changes floating-point precision. When used in an expression out << setprecision(n) or in >> setprecision(n), sets the precision parameter of the stream out or into exactly n.
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. When used in an expression out << setw(n) or in >> setw(n), sets the width parameter of the stream out or in to exactly n.
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
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