noskipws

Noskipws is a manipulation in the C++ iostream library. It is defined in the header <istream> as std::noskipws and serves to modify the formatting state of a stream during formatted input.

The effect of std::noskipws is to clear the skipws flag on the stream (the flag ios_base::skipws). When this flag is not set, formatted input using operator>> will not skip leading whitespace, meaning whitespace characters can be read as data rather than being ignored. By applying std::noskipws, subsequent extractions using operator>> will preserve whitespace at the beginning of the input or between data tokens, depending on the type and context.

A common usage pattern is to read every character, including spaces, by chaining the manipulator with input operations. For example: char c; std::cin >> std::noskipws >> c; reads the next character from standard input regardless of whether it is whitespace. Because noskipws affects formatted input, it is especially useful when processing data where whitespace must be preserved as part of the stream, or when combining with other input methods that handle raw data.

Noskipws is the counterpart to std::skipws. While std::skipws sets the skipws flag to true, std::noskipws unsets it, altering how formatted extractions treat leading whitespace. In many typical input scenarios, the default behavior is to skip whitespace; noskipws is used when that default must be overridden.

Notes: using noskipws with non-character types can lead to input failures if the data begins with whitespace. For reading whitespace-bearing data, other facilities such as get, read, or getline may be more appropriate depending on the task.