NAME

std::basic_streambuf::setg - std::basic_streambuf::setg

Synopsis

protected:
void setg( char_type* gbeg, char_type* gcurr, char_type* gend );

Sets the values of the pointers defining the get area. Specifically, after the call
eback() == gbeg, gptr() == gcurr, egptr() == gend

Parameters

gbeg - pointer to the new beginning of the get area
gcurr - pointer to the new current character (get pointer) in the get area
gend - pointer to the new end of the get area

Return value

(none)

Example

// Run this code

#include <iostream>
#include <sstream>

class null_filter_buf : public std::streambuf {
std::streambuf* src;
char ch; // single-byte buffer
protected:
int underflow() {
traits_type::int_type i;
while ((i = src->sbumpc()) == '\0') ; // skip zeroes
if (!traits_type::eq_int_type(i, traits_type::eof())) {
ch = traits_type::to_char_type(i);
setg(&ch, &ch, &ch+1); // make one read position available
}
return i;
}
public:
null_filter_buf(std::streambuf* buf) : src(buf) {
setg(&ch, &ch+1, &ch+1); // buffer is initially full
}
};

void filtered_read(std::istream& in)
{
std::streambuf* orig = in.rdbuf();
null_filter_buf buf(orig);
in.rdbuf(&buf);
for(char c; in.get(c); )
std::cout << c;
in.rdbuf(orig);
}

int main()
{
char a[] = "This i\0s \0an e\0\0\0xample";
std::istringstream in(std::string(std::begin(a), std::end(a)));
filtered_read(in);
}

Output: