Ch11.12.1: Complete C++ I/O Reference

Stream Classes

Class	Description
`std::istream`	Base input stream
`std::ostream`	Base output stream
`std::iostream`	Base input/output stream
`std::ifstream`	Input file stream
`std::ofstream`	Output file stream
`std::fstream`	Input/output file stream
`std::istringstream`	Input string stream
`std::ostringstream`	Output string stream
`std::stringstream`	Input/output string stream
`std::filebuf`	File buffer (narrow)
`std::wfilebuf`	File buffer (wide)
`std::streambuf`	Base stream buffer


#include <iostream>
#include <fstream>
#include <sstream>

int main() {
    // File streams
    std::ifstream in("input.txt");
    std::ofstream out("output.txt");
    std::fstream both("both.txt", std::ios::in | std::ios::out);

    // String streams
    std::istringstream sin("42 3.14");
    std::ostringstream sout;
    sout << "Value: " << 42;

    int x;
    double y;
    sin >> x >> y;

    std::cout << sout.str() << '\n';
    return 0;
}

Standard Stream Objects

Object	Description
`std::cin`	Standard input stream
`std::cout`	Standard output stream
`std::cerr`	Standard error stream (unbuffered)
`std::clog`	Standard error stream (buffered)
`std::wcin`	Wide standard input stream
`std::wcout`	Wide standard output stream
`std::wcerr`	Wide standard error stream (unbuffered)
`std::wclog`	Wide standard error stream (buffered)

Stream Manipulators

Manipulator	Description
`std::endl`	Output newline and flush
`std::ends`	Output null terminator
`std::flush`	Flush stream
`std::ws`	Skip whitespace (input)
`std::boolalpha`	Use true/false for booleans
`std::noboolalpha`	Use 1/0 for booleans
`std::showbase`	Show base prefix (0x, 0)
`std::noshowbase`	Don’t show base prefix
`std::showpoint`	Show decimal point
`std::noshowpoint`	Don’t show decimal point
`std::showpos`	Show + sign for positive numbers
`std::noshowpos`	Don’t show + sign
`std::skipws`	Skip whitespace on input
`std::noskipws`	Don’t skip whitespace
`std::uppercase`	Use uppercase for hex/scientific
`std::nouppercase`	Use lowercase
`std::unitbuf`	Flush after each output
`std::nounitbuf`	Don’t flush after each output
`std::internal`	Internal padding
`std::left`	Left-align
`std::right`	Right-align
`std::dec`	Decimal base
`std::hex`	Hexadecimal base
`std::oct`	Octal base
`std::fixed`	Fixed-point notation
`std::scientific`	Scientific notation
`std::defaultfloat`	Default floating-point notation


#include <iostream>
#include <iomanip>

int main() {
    // Boolean formatting
    std::cout << std::boolalpha << true << '\n';  // true
    std::cout << std::noboolalpha << true << '\n';  // 1

    // Numeric base
    std::cout << std::hex << 255 << '\n';  // ff
    std::cout << std::showbase << std::hex << 255 << '\n';  // 0xff

    // Floating-point
    double pi = 3.14159;
    std::cout << std::fixed << pi << '\n';  // 3.141590
    std::cout << std::scientific << pi << '\n';  // 3.141590e+00

    // Alignment
    std::cout << std::left << std::setw(10) << 42 << "|\n";  // 42        |
    std::cout << std::right << std::setw(10) << 42 << "|\n";  //         42|

    return 0;
}