d457a43461
interpreting octal breaks parsing of decimal numbers with leading zeros. the manpage listed this in the BUGS section, so we'r going to fix it as this just causes confusion as most callers of atoi() do not expect it.
138 lines
2.5 KiB
Plaintext
138 lines
2.5 KiB
Plaintext
.TH ATOF 2
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.SH NAME
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atof, atoi, atol, atoll, charstod, strtod, strtol, strtoll, strtoul, strtoull \- convert text to numbers
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.SH SYNOPSIS
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.B #include <u.h>
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.br
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.B #include <libc.h>
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.PP
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.nf
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.ta \w'\fLdouble 'u
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.B
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double atof(char *nptr)
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.PP
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.B
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int atoi(char *nptr)
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.PP
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.B
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long atol(char *nptr)
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.PP
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.B
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vlong atoll(char *nptr)
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.PP
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.B
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double charstod(int (*f)(void *), void *a)
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.PP
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.B
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double strtod(char *nptr, char **rptr)
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.PP
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.B
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long strtol(char *nptr, char **rptr, int base)
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.PP
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.B
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vlong strtoll(char *nptr, char **rptr, int base)
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.PP
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.B
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ulong strtoul(char *nptr, char **rptr, int base)
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.PP
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.B
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uvlong strtoull(char *nptr, char **rptr, int base)
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.fi
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.SH DESCRIPTION
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.IR Atof ,
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.IR atoi ,
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.IR atol ,
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and
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.I atoll
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convert a string pointed to by
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.I nptr
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to floating, integer, long integer, and long long integer
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.RB ( vlong )
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representation respectively.
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The first unrecognized character ends the string.
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Leading C escapes are understood, as in
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.I strtol
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with
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.I base
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zero (described below).
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.PP
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.I Atof
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recognizes an optional string of tabs and spaces,
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then an optional sign, then
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a string of digits optionally containing a decimal
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point, then an optional
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.L e
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or
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.L E
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followed
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by an optionally signed integer.
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.PP
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.I Atoi
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and
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.I atol
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recognize an optional string of tabs and spaces,
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then an optional sign, then a string of
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decimal digits.
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.PP
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.IR Strtod ,
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.IR strtol ,
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.IR strtoll ,
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.IR strtoul ,
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and
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.I strtoull
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behave similarly to
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.I atof
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and
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.I atol
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and, if
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.I rptr
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is not zero, set
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.I *rptr
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to point to the input character
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immediately after the string converted.
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.PP
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.IR Strtol ,
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.IR strtoll ,
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.IR strtoul ,
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and
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.IR strtoull
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interpret the digit string in the specified
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.IR base ,
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from 2 to 36,
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each digit being less than the base.
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Digits with value over 9 are represented by letters,
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a-z or A-Z.
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If
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.I base
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is 0, the input is interpreted as an integral constant in
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the style of C (with no suffixed type indicators):
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numbers are octal if they begin with
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.LR 0 ,
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hexadecimal if they begin with
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.L 0x
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or
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.LR 0X ,
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otherwise decimal.
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.PP
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.I Charstod
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interprets floating point numbers in the manner of
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.IR atof ,
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but gets successive characters by calling
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.BR (*\fIf\fP)(a) .
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The last call to
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.I f
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terminates the scan, so it must have returned a character that
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is not a legal continuation of a number.
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Therefore, it may be necessary to back up the input stream one character
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after calling
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.IR charstod .
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.SH SOURCE
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.B /sys/src/libc/port
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.SH SEE ALSO
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.IR fscanf (2)
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.SH DIAGNOSTICS
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Zero is returned if the beginning of the input string is not
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interpretable as a number; even in this case,
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.I rptr
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will be updated.
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