#include <stdlib.h>

long strtol(const char *str, char **endptr, int base);


The strtol() function converts the string in str to a long value. The conversion is done according to the given base, which must be between 2 and 16 inclusive, or be the special value 0.

The string may begin with an arbitrary amount of white space (as determined by isspace()) followed by a single optional +' or-' sign. If base is zero or 16, the string may then include a 0x' prefix, and the number will be read in base 16; otherwise, a zero base is taken as 10 (decimal) unless the next character is `0', in which case it is taken as 8 (octal).

The remainder of the string is converted to a long in the obvious manner, stopping at the first character which is not a valid digit in the given base. (In bases above 10, the letter A' in either upper or lower case represents 10,B' represents 11, and so forth, with `Z' representing 35.)

If endptr is not NULL, strtol() stores the address of the first invalid character in *endptr. If there were no digits at all, however, strtol() stores the original value of str in *endptr. (Thus, if *str is not \0 but **endptr is \0 on return, the entire string was valid.)

Return value