0x20 Treated As 0x00 With Stringstream - C++ - Stack Overflow

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Learn more about Labs 0x20 treated as 0x00 with stringstream Ask Question Asked 4 years, 6 months ago Modified 4 years, 6 months ago Viewed 368 times 1

The following program writes 0x20 to stringstream, then reads the value and it's 0. Why is that and how to write a value so it is read as 0x20?

#include <iostream> #include <sstream> int main() { std::stringstream ss; ss << (char) 0x20; char c; ss >> c; if ( c == 0x20 ) { std::cout << "32"; } else if ( c == 0 ) { std::cout << "0"; } else { std::cout << "other"; } std::cout << '\n'; }

• c++

Share Improve this question Follow asked May 6, 2020 at 13:47 AshleyWilkesAshleyWilkes 82166 silver badges1313 bronze badges 2

• 3 ss >> std::noskipws >> c; it reads whitespace. By default, any whitespaces are discarded when reading by formatted operation. – rafix07 Commented May 6, 2020 at 13:49
• thank you very much! – AshleyWilkes Commented May 6, 2020 at 13:51

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1 Answer 1

Sorted by: Reset to default Highest score (default) Trending (recent votes count more) Date modified (newest first) Date created (oldest first) 4

By default, std::stringstream's >> operator skips over writespace. And in ASCII (a typical but by no means universal encoding). 0x20 is the space character you get when you press that long button on your keyboard.

As there is nothing else on the stream, NUL is output to c.

Introducing the manipulator std::noskipws is the fix; that is ss >> std::noskipws >> c; reads the value as 0x20.

Share Improve this answer Follow edited May 6, 2020 at 14:16 answered May 6, 2020 at 13:51 BathshebaBathsheba 234k3535 gold badges368368 silver badges495495 bronze badges Add a comment |

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