std::basic_istream<CharT,Traits>::gcount
From cppreference.com
std::streamsize gcount() const;
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Returns the number of characters extracted by the last unformatted input operation, or the maximum representable value of std::streamsize if the number is not representable.
The following member functions of basic_istream change the value of subsequent gcount() calls:
- move constructor
- swap()
- get()
- getline()
- ignore()
- read()
- readsome()
- operator>>
The following functions set gcount() to zero:
- constructor
- putback()
- unget()
- peek()
Parameters
(none)
Return value
The number of characters extracted by the last unformatted input operation, or the maximum representable value of std::streamsize if the number is not representable.
Example
Run this code
#include <iostream>
#include <sstream>
int main()
{
char x[20];
std::istringstream stream("Hello World");
stream.read(x, sizeof x);
std::cout << "Characters extracted: " << stream.gcount();
}
Output:
Characters extracted: 11
Defect reports
The following behavior-changing defect reports were applied retroactively to previously published C++ standards.
| DR | Applied to | Behavior as published | Correct behavior |
|---|---|---|---|
| LWG 3464 | C++98 | the return value was unspecified when the result overflows | returns the maximum value |
