1.\" $NetBSD: strtou.3,v 1.3 2015/07/11 15:51:33 wiz Exp $ 2.\" 3.\" Copyright (c) 1990, 1991, 1993 4.\" The Regents of the University of California. All rights reserved. 5.\" 6.\" This code is derived from software contributed to Berkeley by 7.\" Chris Torek and the American National Standards Committee X3, 8.\" on Information Processing Systems. 9.\" 10.\" Redistribution and use in source and binary forms, with or without 11.\" modification, are permitted provided that the following conditions 12.\" are met: 13.\" 1. Redistributions of source code must retain the above copyright 14.\" notice, this list of conditions and the following disclaimer. 15.\" 2. Redistributions in binary form must reproduce the above copyright 16.\" notice, this list of conditions and the following disclaimer in the 17.\" documentation and/or other materials provided with the distribution. 18.\" 3. Neither the name of the University nor the names of its contributors 19.\" may be used to endorse or promote products derived from this software 20.\" without specific prior written permission. 21.\" 22.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32.\" SUCH DAMAGE. 33.\" 34.\" from: @(#)strtoul.3 8.1 (Berkeley) 6/4/93 35.\" 36.\" Created by Kamil Rytarowski, based on ID: 37.\" NetBSD: strtoul.3,v 1.29 2015/03/10 13:00:58 christos Exp 38.\" 39.Dd April 30, 2015 40.Dt STRTOU 3 41.Os 42.Sh NAME 43.Nm strtou 44.Nd convert a string to an uintmax_t integer 45.Sh LIBRARY 46.Lb libc 47.Sh SYNOPSIS 48.In inttypes.h 49.Ft uintmax_t 50.Fo strtou 51.Fa "const char * restrict nptr" 52.Fa "char ** restrict endptr" 53.Fa "int base" 54.Fa "uintmax_t lo" 55.Fa "uintmax_t hi" 56.Fa "int *rstatus" 57.Fc 58.Sh DESCRIPTION 59The 60.Fn strtou 61function converts the string in 62.Fa nptr 63to an 64.Ft uintmax_t 65value. 66The 67.Fn strtou 68function uses internally 69.Xr strtoumax 3 70and ensures that the result is always in the range [ 71.Fa lo .. 72.Fa hi 73]. 74In adddition it always places 75.Dv 0 76on success or a conversion status in the 77.Fa rstatus 78argument, avoiding the 79.Dv errno 80gymnastics the other functions require. 81The 82.Fa rstatus 83argument can be 84.Dv NULL 85if conversion status is to be ignored. 86.Pp 87The string may begin with an arbitrary amount of white space 88(as determined by 89.Xr isspace 3 ) 90followed by a single optional 91.Ql + 92or 93.Ql - 94sign. 95If 96.Fa base 97is zero or 16, 98the string may then include a 99.Ql 0x 100prefix, 101and the number will be read in base 16; otherwise, a zero 102.Fa base 103is taken as 10 (decimal) unless the next character is 104.Ql 0 , 105in which case it is taken as 8 (octal). 106.Pp 107The remainder of the string is converted to an 108.Em uintmax_t 109value in the obvious manner, 110stopping at the end of the string 111or at the first character that does not produce a valid digit 112in the given base. 113(In bases above 10, the letter 114.Ql A 115in either upper or lower case 116represents 10, 117.Ql B 118represents 11, and so forth, with 119.Ql Z 120representing 35.) 121.Pp 122If 123.Fa endptr 124is non-nil, 125.Fn strtou 126stores the address of the first invalid character in 127.Fa *endptr . 128If there were no digits at all, however, 129.Fn strtou 130stores the original value of 131.Fa nptr 132in 133.Fa *endptr . 134(Thus, if 135.Fa *nptr 136is not 137.Ql \e0 138but 139.Fa **endptr 140is 141.Ql \e0 142on return, the entire string was valid.) 143.Sh RETURN VALUES 144The 145.Fn strtou 146function 147always returns the closest value in the range specified by 148the 149.Fa lo 150and 151.Fa hi 152arguments. 153.Pp 154The 155.Va errno 156value is guaranteed to be left unchanged. 157.Pp 158Errors are stored as the conversion status in the 159.Fa rstatus 160argument. 161.Sh EXAMPLES 162The following example will always return a number in 163.Dv [1..99] 164range no matter what the input is, and warn if the conversion failed. 165.Bd -literal -offset indent 166int e; 167uintmax_t lval = strtou(buf, NULL, 0, 1, 99, &e); 168if (e) 169 warnc(e, "conversion of `%s' to a number failed, using %ju", 170 buf, lval); 171.Ed 172.Sh ERRORS 173.Bl -tag -width Er 174.It Bq Er ECANCELED 175The string did not contain any characters that were converted. 176.It Bq Er EINVAL 177The 178.Ar base 179is not between 2 and 36 and does not contain the special value 0. 180.It Bq Er ENOTSUP 181The string contained non-numeric characters that did not get converted. 182In this case, 183.Fa endptr 184points to the first unconverted character. 185.It Bq Er ERANGE 186The given string was out of range; the value converted has been clamped; or 187the range given was invalid, i.e. 188.Fa lo 189\*[Gt] 190.Fa hi . 191.El 192.Sh SEE ALSO 193.Xr atof 3 , 194.Xr atoi 3 , 195.Xr atol 3 , 196.Xr atoll 3 , 197.Xr strtod 3 , 198.Xr strtoi 3 , 199.Xr strtoimax 3 , 200.Xr strtol 3 , 201.Xr strtoll 3 , 202.Xr strtoul 3 , 203.Xr strtoull 3 , 204.Xr strtoumax 3 205.Sh STANDARDS 206The 207.Fn strtou 208function is a 209.Nx 210extension. 211.Sh HISTORY 212The 213.Fn strtou 214function first appeared in 215.Nx 7 . 216.Ox 217introduced the 218.Fn strtonum 3 219function for the same purpose, but the interface makes it impossible to 220properly differentiate illegal returns. 221.Sh BUGS 222Ignores the current locale. 223