std::basic_streambuf<CharT,Traits>::setg

#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円')
 ; // 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 i0円s 0円an e0円0円0円xample";
 std::istringstream in(std::string (std::begin (a), std::end (a)));
 filtered_read(in);
}

This is an example