atof, atoi, atol, atoll, charstod, strtod, strtol, strtoll, strtoul, strtoull – convert text to numbers


#include <u.h>
#include <libc.h>

double atof(char *nptr)

int atoi(char *nptr)

long atol(char *nptr)

vlong atoll(char *nptr)

double charstod(int (*f)(void *), void *a)

double strtod(char *nptr, char **rptr)

long strtol(char *nptr, char **rptr, int base)

vlong strtoll(char *nptr, char **rptr, int base)

ulong strtoul(char *nptr, char **rptr, int base)

uvlong strtoull(char *nptr, char **rptr, int base)


Atof, atoi, atol, and atoll convert a string pointed to by nptr to floating, integer, long integer, and long long integer (vlong) representation respectively. The first unrecognized character ends the string. Leading C escapes are understood, as in strtol with base zero (described below).

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 e or E 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, strtoll, strtoul, and strtoull 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, strtoll, strtoul, and strtoull 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 suffixed type indicators): numbers are octal if they begin with 0, hexadecimal if they begin with 0x or 0X, otherwise decimal.

Charstod interprets floating point numbers in the manner of atof, but gets successive 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 continuation of a number. Therefore, it may be necessary to back up the input stream one character after calling charstod.






Zero is returned if the beginning of the input string is not interpretable as a number; even in this case, rptr will be updated.