man3/strtol.3

   1 .\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
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  23 .\" References consulted:
  24 .\"     Linux libc source code
  25 .\"     Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
  26 .\"     386BSD man pages
  27 .\" Modified Sun Jul 25 10:53:39 1993 by Rik Faith (faith@cs.unc.edu)
  28 .\" Added correction due to nsd@bbc.com (Nick Duffek) - aeb, 950610
  29 .TH STRTOL 3  2002-05-30 "GNU" "Linux Programmer's Manual"
  30 .SH NAME
  31 strtol, strtoll, strtoq \- convert a string to a long integer
  32 .SH SYNOPSIS
  33 .nf
  34 .B #include <stdlib.h>
  35 .sp
  36 .BI "long int"
  37 .BI "strtol(const char *" nptr ", char **" endptr ", int " base );
  38 .sp
  39 .BI "long long int"
  40 .BI "strtoll(const char *" nptr ", char **" endptr ", int " base );
  41 .fi
  42 .SH DESCRIPTION
  43 The \fBstrtol()\fP function converts the initial part of the string
  44 in \fInptr\fP to a long integer value according to the given \fIbase\fP,
  45 which must be between 2 and 36 inclusive, or be the special value 0.
  46 .PP
  47 The string must begin with an arbitrary amount of white space (as
  48 determined by
  49 .BR isspace (3))
  50 followed by a single optional `+' or `-'
  51 sign.  If \fIbase\fP is zero or 16, the string may then include a
  52 `0x' prefix, and the number will be read in base 16; otherwise, a
  53 zero \fIbase\fP is taken as 10 (decimal) unless the next character
  54 is `0', in which case it is taken as 8 (octal).
  55 .PP
  56 The remainder of the string is converted to a long int value
  57 in the obvious manner, stopping at the first character which is not a
  58 valid digit in the given base.  (In bases above 10, the letter `A' in
  59 either upper or lower case represents 10, `B' represents 11, and so
  60 forth, with `Z' representing 35.)
  61 .PP
  62 If \fIendptr\fP is not NULL, \fBstrtol()\fP stores the address of the
  63 first invalid character in \fI*endptr\fP.  If there were no digits at
  64 all, \fBstrtol()\fP stores the original value of \fInptr\fP in
  65 \fI*endptr\fP (and returns 0).
  66 In particular, if \fI*nptr\fP is not `\\0' but \fI**endptr\fP
  67 is `\\0' on return, the entire string is valid.
  68 .PP
  69 The
  70 .B strtoll()
  71 function works just like the
  72 .B strtol()
  73 function but returns a long long integer value.
  74 .SH "RETURN VALUE"
  75 The \fBstrtol()\fP function returns the result of the conversion,
  76 unless the value would underflow or overflow.  If an underflow occurs,
  77 \fBstrtol()\fP returns LONG_MIN.  If an overflow occurs, \fBstrtol()\fP
  78 returns LONG_MAX.  In both cases, \fIerrno\fP is set to ERANGE.
  79 Precisely the same holds for
  80 .B strtoll()
  81 (with LLONG_MIN and LLONG_MAX instead of LONG_MIN and LONG_MAX).
  82 .SH ERRORS
  83 .TP
  84 .B EINVAL
  85 (not in C99)
  86 The given
  87 .I base
  88 contains an unsupported value.
  89 .TP
  90 .B ERANGE
  91 The resulting value was out of range.
  92 .LP
  93 The implementation may also set \fIerrno\fP to \fBEINVAL\fP in case
  94 no conversion was performed (no digits seen, and 0 returned).
  95 .SH NOTES
  96 In locales other than the "C" locale, also other strings may be accepted.
  97 (For example, the thousands separator of the current locale may be
  98 supported.)
  99 .LP
 100 BSD also has
 101 .sp
 102 .in +4n
 103 .nf
 104 .BI "quad_t"
 105 .BI "strtoq(const char *" nptr ", char **" endptr ", int " base );
 106 .sp
 107 .in -4n
 108 .fi
 109 with completely analogous definition.
 110 Depending on the wordsize of the current architecture, this
 111 may be equivalent to
 112 .B strtoll()
 113 or to
 114 .BR strtol() .
 115 .SH "CONFORMING TO"
 116 .B strtol()
 117 conforms to SVID 3, BSD 4.3, ISO 9899 (C99) and POSIX, and
 118 .B strtoll()
 119 to ISO 9899 (C99) and POSIX 1003.1-2001.
 120 .SH "SEE ALSO"
 121 .BR atof (3),
 122 .BR atoi (3),
 123 .BR atol (3),
 124 .BR strtod (3),
 125 .BR strtoul (3)