getline

Syntax:

    istream& istream::getline( char* buffer, streamsize num );
    istream& istream::getline( char* buffer, streamsize num, char delim );

The getline() function is used with input streams. The version without a char delim argument effectively sets the delimiter to a newline character. getline() reads characters into buffer until either:

  • num - 1 characters have been read,
  • an EOF is encountered,
  • or, until the character delim is read. The delim character is not put into buffer.

If the delim character (newline normally) is not read, the input stream is set to a failure state.

For example, the following code uses the getline function to display the first 99 characters (one character is reserved for null-termination) or one line at a time from a text file – whichever comes first – (until EOF or a line longer than 99 characters is encountered):

    ifstream fin("tmp.dat");
 
    int MAX_LENGTH = 100;
    char line[MAX_LENGTH];
 
    while( fin.getline(line, MAX_LENGTH) ) {
      cout << "read line: " << line << endl;
    }

If you'd like to read lines from a file into strings instead of character arrays, consider using the string getline function.

Those using a Microsoft compiler may find that getline reads an extra character, and should consult the documentation on the Microsoft getline bug.

Related Topics: gcount, get, string getline, ignore, read