std::basic_streambuf::setg - cppreference.com

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# std::basic_streambuf::setg

From cppreference.com
< cpp‎ | io‎ | basic streambuf

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

### [edit] 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

### [edit] Return value

(none)

### [edit] Example

[edit]
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() {
            while( (ch= src->sbumpc()) == '\0') ; // skip zeroes
            setg(&ch, &ch, &ch+1); // make one read position available
            return ch; // may return EOF
        }
    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

### [edit] See also

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

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