TH ATOF 2
SH NAME
atof, atoi, atol, atoll, charstod, strtod, strtol, strtoll, strtoul, strtoull \- convert text to numbers
SH SYNOPSIS
B #include <u.h>
br
B #include <libc.h>
PP
nf
ta \w'\fLdouble 'u
B
double atof(char *nptr)
PP
B
int atoi(char *nptr)
PP
B
long atol(char *nptr)
PP
B
vlong atoll(char *nptr)
PP
B
double charstod(int (*f)(void *), void *a)
PP
B
double strtod(char *nptr, char **rptr)
PP
B
long strtol(char *nptr, char **rptr, int base)
PP
B
vlong strtoll(char *nptr, char **rptr, int base)
PP
B
ulong strtoul(char *nptr, char **rptr, int base)
PP
B
uvlong strtoull(char *nptr, char **rptr, int base)
fi
SH DESCRIPTION
IR Atof ,
IR atoi ,
IR atol ,
and
I atoll
convert a string pointed to by
I nptr
to floating, integer, long integer, and long long integer
RB ( vlong )
representation respectively.
The first unrecognized character ends the string.
Leading C escapes are understood, as in
I strtol
with
I base
zero (described below).
PP
I 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
L e
or
L E
followed
by an optionally signed integer.
PP
I Atoi
and
I atol
recognize an optional string of tabs and spaces,
then an optional sign, then a string of
decimal digits.
PP
IR Strtod ,
IR strtol ,
IR strtoll ,
IR strtoul ,
and
I strtoull
behave similarly to
I atof
and
I atol
and, if
I rptr
is not zero, set
I *rptr
to point to the input character
immediately after the string converted.
PP
IR Strtol ,
IR strtoll ,
IR strtoul ,
and
IR strtoull
interpret the digit string in the specified
IR 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
I 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
LR 0 ,
hexadecimal if they begin with
L 0x
or
LR 0X ,
otherwise decimal.
PP
I Charstod
interprets floating point numbers in the manner of
IR atof ,
but gets successive characters by calling
BR (*\fIf\fP)(a) .
The last call to
I 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
IR charstod .
SH SOURCE
B /sys/src/libc/port
SH SEE ALSO
IR fscanf (2)
SH DIAGNOSTICS
Zero is returned if the beginning of the input string is not
interpretable as a number; even in this case,
I rptr
will be updated.
