std::skipws

ios_base& skipws (ios_base& str);

Skip whitespaces

Sets the skipws format flag for the str stream.

When the skipws format flag is set, as many whitespace characters as necessary are read and discarded from the stream until a non-whitespace character is found before. This applies to every formatted input operation performed with operator>> on the stream.

Tab spaces, carriage returns and blank spaces are all considered whitespaces (see isspace).

This flag can be unset with the noskipws manipulator, forcing extraction operations to consider leading whitepaces as part of the content to be extracted.

For standard streams, the skipws flag is set on initialization.

Parameters

str: Stream object whose format flag is affected.
Because this function is a manipulator, it is designed to be used alone with no arguments in conjunction with the insertion (<<) and extraction (>>) operations on streams (see example below).

Return Value

Argument str.

Example

// skipws flag example
#include <iostream>     // std::cout, std::skipws, std::noskipws
#include <sstream>      // std::istringstream

int main () {
  char a, b, c;

  std::istringstream iss ("  123");
  iss >> std::skipws >> a >> b >> c;
  std::cout << a << b << c << '\n';

  iss.seekg(0);
  iss >> std::noskipws >> a >> b >> c;
  std::cout << a << b << c << '\n';
  return 0;
}

Output:

123
  1

Notice that in the first set of extractions, the leading spaces were ignored, while in the second they were extracted as valid characters.

Data races

Modifies str. Concurrent access to the same stream object may cause data races.

Exception safety

Basic guarantee: if an exception is thrown, str is in a valid state.

types

manipulators

other functions