term% cat index.txt ATOF(2) System Calls Manual ATOF(2)
NAME
atof, atoi, atol, charstod, strtod, strtol, strtoul - convert text to
numbers
SYNOPSIS
#include <u.h>
#include <libc.h>
double atof(char *nptr)
int atoi(char *nptr)
long atol(char *nptr)
double charstod(int (*f)(void *), void *a)
double strtod(char *nptr, char **rptr)
long strtol(char *nptr, char **rptr, int base)
ulong strtoul(char *nptr, char **rptr, int base)
/* Alef only */
int strtoi(byte *nptr, byte **rptr, int base)
uint strtoui(byte *nptr, byte **rptr, int base)
float strtof(byte *nptr, byte **rptr);
DESCRIPTION
Atof, atoi, and atol convert a string pointed to by nptr to floating,
integer, and long integer representation respectively. The first un‐
recognized character ends the string. Leading C escapes are under‐
stood, as in strtol with base zero.
Atof recognizes an optional string of tabs and spaces, then an optional
sign, then a string of digits optionally containing a decimal point,
then an optional or followed by an optionally signed integer.
Atoi and atol recognize an optional string of tabs and spaces, then an
optional sign, then a string of decimal digits.
Strtod, strtol, and strtoul behave similarly to atof and atol and, if
rptr is not zero, set *rptr to point to the input character immediately
after the string converted.
Strtol and strtoul interpret the digit string in the specified base,
from 2 to 36, each digit being less than the base. Digits with value
over 9 are represented by letters, a-z or A-Z. If base is 0, the input
is interpreted as an integral constant in the style of C (with no suf‐
fixed type indicators): numbers are octal if they begin with hexadeci‐
mal if they begin with or otherwise decimal. Strtoul does not recog‐
nize signs.
Charstod interprets floating point numbers like atof, but it gets suc‐
cessive characters by calling (*f)(a). The last call to f terminates
the scan, so it must have returned a character that is not a legal con‐
tinuation of a number. Therefore, it may be necessary to back up the
input stream one character after calling charstod.
Alef
The routines strtol and strtoul are renamed strtoi and strtoui and re‐
turn type int and uint. There is no charstod or atof. Instead, strtof
is like a floating-point base 10 strtoi.
SOURCE
/sys/src/libc/port
SEE ALSO
fscanf(2)
DIAGNOSTICS
Zero is returned if the beginning of the input string is not inter‐
pretable as a number; even in this case, rptr will be updated.
These routines set errstr.
BUGS
Atoi and atol accept octal and hexadecimal numbers in the style of C,
contrary to the ANSI specification.
ATOF(2)