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researchv10 Dan Cross

.TH ATOF 3
.CT 2 data_man math
.SH NAME
atof, atoi, atol, strtod, strtol, strtoul \(mi convert ASCII to numbers
.SH SYNOPSIS
.nf
.B double atof(nptr)
.B char *nptr;
.PP
.B int atoi(nptr)
.B char *nptr;
.PP
.B long atol(nptr)
.B char *nptr;
.PP
.B double strtod(nptr, rptr)
.B char *nptr, **rptr;
.PP
.B "long strtol(nptr, rptr, base)
.B char *nptr, **rptr;
.PP
.B "unsigned long strtoul(nptr, rptr, base)
.B char *nptr, **rptr;
.fi
.SH DESCRIPTION
.IR Atof ,
.IR atoi ,
and
.I atol
convert a string pointed to by
.I nptr
to floating, integer, and long integer
representation respectively.
The first unrecognized character ends the string.
.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
.I Strtod,
.I strtol,
and
.I strtoul,
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
.I Strtol
and
.I strtoul
interpret the digit string in the specified
.I 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.
.I Strtoul
does not recognize signs.
.SH SEE ALSO
.IR scanf (3)
.SH DIAGNOSTICS
Zero is returned if the begining of the input string is not
interpretable as a number.
.PP
If overflow is detected by
.I atof,
.I strtod,
.I strtol,
or
.I strtoul, 
a maximum value of the correct sign is returned and
.I errno
is set to
.BR ERANGE .
.SH BUGS
.I Atoi
and
.I atol
have no provisions for overflow.

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