Discards leading whitespace from an input stream.

Behaves as anUnformattedInputFunction, except thatis.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 callssetstate(eofbit) but does not setfailbit; this does not apply if theeofbit is already set onis prior to the call tows, in which case the construction of the sentry object would setfailbit).

• the next available characterc in the input sequence is not whitespace as determined bystd::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 asin>> std::ws for anyin of typestd::basic_istream.

[edit]Parameters

[edit]Return value

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

[edit]Notes

Ifeofbit is set on the stream prior to the call, the construction of the sentry object will setfailbit.

[edit]Example

#include <iomanip>#include <iostream>#include <istream>#include <sstream>#include <string> int main(){for(constchar* str:{"     #1 test","\t #2 test","#3 test"}){std::string line;std::getline(std::istringstream{str}, line);std::cout<<"getline returns:\t"<<std::quoted(line)<<'\n'; std::istringstream iss{str};std::getline(iss>> std::ws, line);std::cout<<"ws + getline returns:\t"<<std::quoted(line)<<'\n';}}

getline returns:"     #1 test"ws + getline returns:"#1 test"getline returns:" #2 test"ws + getline returns:"#2 test"getline returns:"#3 test"ws + getline returns:"#3 test"

[edit]Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

[edit]See also

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