std::ws

 

C++

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Input/output library

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streamoff

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Input/output manipulators

Floating-point formatting
showpointnoshowpoint setprecision	fixedscientifichexfloatdefaultfloat (C++11)(C++11)
Integer formatting
setbase showbasenoshowbase	dechexoct
Boolean formatting
boolalphanoboolalpha
Field width and fill control
setfill setw	internalleftright
Other formatting
showposnoshowpos	uppercasenouppercase
Whitespace processing
ws ends	skipwsnoskipws
Output flushing
flush endl	unitbufnounitbuf
Status flags manipulation
resetiosflags	setiosflags
Time and money I/O
get_money (C++11) get_time (C++11)	put_money (C++11) put_time (C++11)

 

Defined in header <istream>
template< class CharT, class Traits > std::basic_istream<CharT,Traits>& ws( std::basic_istream<CharT, Traits>& is );

Discards leading whitespace from an input stream.

Behaves as an UnformattedInputFunction, except that is.gcount() is not modified. After constructing and checking the sentry object, extracts characters from the stream and discards them until any one of the following conditions occurs:

• end of file condition occurs in the input sequence (in which case the function calls setstate(eofbit) but does not set failbit.

• the next available character c in the input sequence is not whitespace as determined by std::isspace(c, is.getloc()). The non-whitespace character is not extracted.

This is an input-only I/O manipulator, it may be called with an expression such as in >> std::ws for any in of type std::basic_istream.

Parameters

is

-

reference to input stream

Return value

is (reference to the stream after extraction of consecutive whitespace)

Example

Run this code

#include <iostream>
#include <sstream>
 
int main()
{
    std::istringstream s("     this is a test");
    std::string line;
    getline(s >> std::ws, line);
    std::cout << "ws + getline returns: \"" << line << "\"\n";
}

Output:

ws + getline returns: "this is a test"

See also

ignore

extracts and discards characters until the given character is found (public member function of std::basic_istream)