NAME

strtol, atol, atoi − convert string to integer

SYNOPSIS

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

long atol (str)
char ∗str;

int atoi (str)
char ∗str;

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 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 thusly: 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(3C), strtod(3C), scanf(3S). 

BUGS

Overflow conditions are ignored. 

Hewlett-Packard Company  —  Version B.1,  May 11, 2021