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

From cppreference.com
< cpp‎ | io‎ | basic streambuf

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:

    This is an example

### See also

setp | repositions the beginning, next, and end pointers of the output sequence (protected member function)

Retrieved from "https://en.cppreference.com/mwiki/index.php?title=cpp/io/basic_streambuf/setg&oldid=124725"