NAME

strtol, strtoul − convert string to integer

SYNOPSIS

long strtol (str, ptr, base)
char ∗str, ∗∗ptr;
int base;

unsigned long strtoul (str, ptr, base)
char ∗str, ∗∗ptr;
int base;

DESCRIPTION

strtol returns as a long integer the value represented by the character string pointed to by str. The string is scanned up to the first character inconsistent with the base. Leading ”white-space” characters (as defined by isspace in ctype(3C)) are ignored. 

If the value of ptr is not (char ∗∗)NULL, a pointer to the character terminating the scan is returned in the location pointed to by ptr. If no integer can be formed, that location is set to str, and zero is returned.

If base is greater than 1 and less than 36, it is used as the base for conversion.  After an optional leading sign, leading zeros are ignored, and ”0x” or ”0X” is ignored if base is 16. 

If base is zero, the string itself determines the base as follows: After an optional leading sign a leading zero indicates octal conversion, and a leading ”0x” or ”0X” hexadecimal conversion.  Otherwise, decimal conversion is used. 

All other values of base are invalid. 

Truncation from long to int can, of course, take place upon assignment or by an explicit cast. 

Strtoul behaves just like strtol except that it returns an unsigned long, rather than a long. 

DIAGNOSTICS

By default strtol ignores overflow conditions, except in programs which are linked in one of the ANSI C compilation modes and in programs linked in the 88open OCS-compliant mode.  This allows for upward compatibility for programs that relied on strtol to translate constants that require unsigned long representation before strtoul became available.  Strtoul always detects overflow conditions. 

When strtol detects an overflow, it returns either LONG_MAX or LONG_MIN (depending upon the sign of str), and sets the value of errno to ERANGE.  If strtoul detects an overflow it returns ULONG_MAX, and also sets the value of errno to ERANGE. 

If the value of base is invalid errno is set to EINVAL, and 0 is returned. 

SEE ALSO

ctype(3C), scanf(3S), strtod(3C), atof(3C), atol(3C). 

CX/UX Programmer’s Reference Manual