long int atol(const char *str
The string pointed to by the argument str is converted to
a long integer (type
long int). Any initial
whitespace characters are skipped (space, tab, carriage return,
new line, vertical tab, or formfeed). The number may consist of
an optional sign and a string of digits. Conversion stops when
the first unrecognized character is reached.
On success the converted number is returned. If the number
cannot be converted, then
0 is returned.