Chapter 57: std::iomanip

hex - use hexadecimal base for integer I/O

basefield - dec|oct|hex|0 useful for masking operations

left - left adjustment(add fill characters to the right)

right - right adjustment (adds fill characters to the left)

internal - internal adjustment (adds fill characters to the internal designated point)

adjustfield - left|right|internal. Useful for masking operations

scientific - generate floating point types using scientific notation, or hex notation if combined with fixed

fixed - generate floating point types using fixed notation, or hex notation if combined with scientific

floatfield - scientific|fixed|(scientific|fixed)|0. Useful for masking operations

boolalpha - insert and extract bool type in alphanumeric format

showbase - generate a prefix indicating the numeric base for integer output, require the currency indicator in monetary I/O

showpoint - generate a decimal-point character unconditionally for floating-point number output

showpos - generate a + character for non-negative numeric output

skipws - skip leading whitespace before certain input operations

unitbuf flush the output after each output operation

uppercase - replace certain lowercase letters with their uppercase equivalents in certain output output operations

Example of manipulators:

#include <iostream> #include <string> #include<iomanip> int main()

{

int l_iTemp = 47;

std::cout<< std::resetiosflags(std::ios_base::basefield); std::cout<<std::setiosflags( std::ios_base::oct)<<l_iTemp<<std::endl; //output: 57

std::cout<< std::resetiosflags(std::ios_base::basefield); std::cout<<std::setiosflags( std::ios_base::hex)<<l_iTemp<<std::endl; //output: 2f

std::cout<<std::setiosflags( std::ios_base::uppercase)<<l_iTemp<<std::endl; //output 2F

std::cout<<std::setfill('0')<<std::setw(12); std::cout<<std::resetiosflags(std::ios_base::uppercase); std::cout<<std::setiosflags( std::ios_base::right)<<l_iTemp<<std::endl; //output: 00000000002f

std::cout<<std::resetiosflags(std::ios_base::basefield|std::ios_base::adjustfield); std::cout<<std::setfill('.')<<std::setw(10);

std::cout<<std::setiosflags( std::ios_base::left)<<l_iTemp<<std::endl; //output: 47........

std::cout<<std::resetiosflags(std::ios_base::adjustfield)<<std::setfill('#'); std::cout<<std::setiosflags(std::ios_base::internal|std::ios_base::showpos); std::cout<<std::setw(10)<<l_iTemp<<std::endl;

//output +#######47

double l_dTemp = -1.2; double pi = 3.14159265359;

std::cout<<pi<<" "<<l_dTemp<<std::endl; //output +3.14159 -1.2

std::cout<<std::setiosflags(std::ios_base::showpoint)<<l_dTemp<<std::endl; //output -1.20000 std::cout<<setiosflags(std::ios_base::scientific)<<pi<<std::endl; //output: +3.141593e+00

std::cout<<std::resetiosflags(std::ios_base::floatfield); std::cout<<setiosflags(std::ios_base::fixed)<<pi<<std::endl; //output: +3.141593

bool b = true; std::cout<<std::setiosflags(std::ios_base::unitbuf|std::ios_base::boolalpha)<<b; //output: true

return 0;

}

Section 57.4: std::setw

int val = 10;

// val will be printed to the extreme left end of the output console: std::cout << val << std::endl;

// val will be printed in an output field of length 10 starting from right end of the field: std::cout << std::setw(10) << val << std::endl;

This outputs:

10

10

1234567890

(where the last line is there to aid in seeing the character o sets).

Sometimes we need to set the width of the output field, usually when we need to get the output in some structured and proper layout. That can be done using std::setw of std::iomanip.

The syntax for std::setw is:

std::setw(int n)

where n is the length of the output field to be set