std::left, std::right, std::internal
From cppreference.com
C++
Feature test macros (C++20)
Concepts library (C++20)
Metaprogramming library (C++11)
Ranges library (C++20)
Filesystem library (C++17)
Concurrency support library (C++11)
Execution control library (C++26)
Input/output library
Print functions (C++23)
Buffers
(C++23)
(C++98/26*)
(C++20)
Streams
Abstractions
File I/O
String I/O
Array I/O
(C++23)
(C++23)
(C++23)
(C++98/26*)
(C++98/26*)
(C++98/26*)
Synchronized Output
(C++20)
Types
Error category interface
(C++11)
(C++11)
Input/output manipulators
Floating-point formatting
(C++11)(C++11)
Integer formatting
Boolean formatting
Field width and fill control
Other formatting
Whitespace processing
Output flushing
(C++20)(C++20)
Status flags manipulation
Time and money I/O
Quoted manipulator
(C++14)
Defined in header
<ios>
std::ios_base & left( std::ios_base & str );
(1)
std::ios_base & right( std::ios_base & str );
(2)
std::ios_base & internal( std::ios_base & str );
(3)
Modifies the positioning of the fill characters in an output stream. left and right apply to any type being output, internal applies to integer, floating-point, and monetary output. Has no effect on input.
1) Sets the
adjustfield of the stream str to left as if by calling str.setf(std::ios_base::left, std::ios_base::adjustfield ).2) Sets the
adjustfield of the stream str to right as if by calling str.setf(std::ios_base::right, std::ios_base::adjustfield ).3) Sets the
adjustfield of the stream str to internal as if by calling str.setf(std::ios_base::internal, std::ios_base::adjustfield ).The initial default for standard streams is equivalent to right.
This is an I/O manipulator. It may be called with an expression such as out << std::left for any out of type std::basic_ostream or with an expression such as in >> std::left for any in of type std::basic_istream .
Contents
[edit] Parameters
str
-
reference to I/O stream
[edit] Return value
str (reference to the stream after manipulation).
[edit] Example
Run this code
#include <iomanip> #include <iostream> #include <locale> int main() { std::cout.imbue(std::locale ("en_US.utf8")); std::cout << "Default positioning:\n" << std::setfill ('*') << std::setw (12) << -1.23 << '\n' << std::setw (12) << std::hex << std::showbase << 42 << '\n' << std::setw (12) << std::put_money (123, true) << "\n\n"; std::cout << "Left positioning:\n" << std::left << std::setw (12) << -1.23 << '\n' << std::setw (12) << 42 << '\n' << std::setw (12) << std::put_money (123, true) << "\n\n"; std::cout << "Internal positioning:\n" << std::internal << std::setw (12) << -1.23 << '\n' << std::setw (12) << 42 << '\n' << std::setw (12) << std::put_money (123, true) << "\n\n"; std::cout << "Right positioning:\n" << std::right << std::setw (12) << -1.23 << '\n' << std::setw (12) << 42 << '\n' << std::setw (12) << std::put_money (123, true) << '\n'; }
Output:
Default positioning: *******-1.23 ********0x2a ***USD *1.23 Left positioning: -1.23******* 0x2a******** USD *1.23*** Internal positioning: -*******1.23 0x********2a USD ****1.23 Right positioning: *******-1.23 ********0x2a ***USD *1.23