STRTOL(S) UNIX System V STRTOL(S)
Name
strtol, atol, atoi - convert string to integer
Syntax
long strtol (str, ptr, base)
char *str, **ptr;
int base;
long atol (str)
char *str;
int atoi (str)
char *str;
Description
The strtol function 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(S)) 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 positive (and not greater 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.
After an optional leading sign a leading zero indicates
octal conversion, and a leading ``0x'' or ``0X'' hexadecimal
conversion. Otherwise, decimal conversion is used.
Truncation from long to int can, of course, take place upon
assignment or by an explicit cast.
atol(str) is equivalent to strtol(str, (char **)NULL, 10).
atoi(str) is equivalent to (int) strtol(str, (char **)NULL,
10).
See Also
ctype(S), scanf(S), strtod(S)
Diagnostics
If the argument ptr is a null-pointer, the function strtol
will return the value of the string str as a long integer.
If the argument ptr is not NULL, the function strtol will
return the value of the string str as a long integer, and a
pointer to the character terminating the scan will be
returned in the location pointed to by ptr.
If no integer can be formed, that location is set to the
argument str and the function strtol returns 0.
Note
Overflow conditions are ignored.
Standards Conformance
atoi and atol are conformant with:
AT&T SVID Issue 2, Select Code 307-127;
The X/Open Portability Guide II of January 1987;
ANSI X3.159-198X C Language Draft Standard, May 13,
1988;
IEEE POSIX Std 1003.1-1988 with C Standard Language-
Dependent System Support;
and NIST FIPS 151-1.
strtol is conformant with:
AT&T SVID Issue 2, Select Code 307-127;
The X/Open Portability Guide II of January 1987;
and ANSI X3.159-198X C Language Draft Standard, May 13,
1988.
(printed 6/20/89)