1.\" Copyright (c) 1990, 1991, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" Chris Torek and the American National Standards Committee X3, 6.\" on Information Processing Systems. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 3. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)strtoul.3 8.1 (Berkeley) 6/4/93 33.\" 34.Dd August 21, 2023 35.Dt STRTOUL 3 36.Os 37.Sh NAME 38.Nm strtoul , strtoull , strtoumax , strtouq 39.Nd "convert a string to an" 40.Vt "unsigned long" , "unsigned long long" , uintmax_t , 41or 42.Vt u_quad_t 43integer 44.Sh LIBRARY 45.Lb libc 46.Sh SYNOPSIS 47.In stdlib.h 48.In limits.h 49.Ft "unsigned long" 50.Fn strtoul "const char * restrict nptr" "char ** restrict endptr" "int base" 51.Ft "unsigned long long" 52.Fn strtoull "const char * restrict nptr" "char ** restrict endptr" "int base" 53.In inttypes.h 54.Ft uintmax_t 55.Fn strtoumax "const char * restrict nptr" "char ** restrict endptr" "int base" 56.In sys/types.h 57.In stdlib.h 58.In limits.h 59.Ft u_quad_t 60.Fn strtouq "const char *nptr" "char **endptr" "int base" 61.Sh DESCRIPTION 62The 63.Fn strtoul 64function 65converts the string in 66.Fa nptr 67to an 68.Vt "unsigned long" 69value. 70The 71.Fn strtoull 72function 73converts the string in 74.Fa nptr 75to an 76.Vt "unsigned long long" 77value. 78The 79.Fn strtoumax 80function 81converts the string in 82.Fa nptr 83to an 84.Vt uintmax_t 85value. 86The 87.Fn strtouq 88function 89converts the string in 90.Fa nptr 91to a 92.Vt u_quad_t 93value. 94The conversion is done according to the given 95.Fa base , 96which must be between 2 and 36 inclusive, 97or be the special value 0. 98.Pp 99The string may begin with an arbitrary amount of white space 100(as determined by 101.Xr isspace 3 ) 102followed by a single optional 103.Ql + 104or 105.Ql - 106sign. 107If 108.Fa base 109is zero or 16, 110the string may then include a 111.Dq Li 0b 112prefix, and the number will be read in base 2; or it may include a 113.Dq Li 0x 114prefix, 115and the number will be read in base 16; otherwise, a zero 116.Fa base 117is taken as 10 (decimal) unless the next character is 118.Ql 0 , 119in which case it is taken as 8 (octal). 120.Pp 121The remainder of the string is converted to an 122.Vt "unsigned long" 123value in the obvious manner, 124stopping at the end of the string 125or at the first character that does not produce a valid digit 126in the given base. 127(In bases above 10, the letter 128.Ql A 129in either upper or lower case 130represents 10, 131.Ql B 132represents 11, and so forth, with 133.Ql Z 134representing 35.) 135.Pp 136If 137.Fa endptr 138is not 139.Dv NULL , 140.Fn strtoul 141stores the address of the first invalid character in 142.Fa *endptr . 143If there were no digits at all, however, 144.Fn strtoul 145stores the original value of 146.Fa nptr 147in 148.Fa *endptr . 149(Thus, if 150.Fa *nptr 151is not 152.Ql \e0 153but 154.Fa **endptr 155is 156.Ql \e0 157on return, the entire string was valid.) 158.Sh RETURN VALUES 159The 160.Fn strtoul , 161.Fn strtoull , 162.Fn strtoumax 163and 164.Fn strtouq 165functions 166return either the result of the conversion 167or, if there was a leading minus sign, 168the negation of the result of the conversion, 169unless the original (non-negated) value would overflow; 170in the latter case, 171.Fn strtoul 172returns 173.Dv ULONG_MAX , 174.Fn strtoull 175returns 176.Dv ULLONG_MAX , 177.Fn strtoumax 178returns 179.Dv UINTMAX_MAX , 180and 181.Fn strtouq 182returns 183.Dv ULLONG_MAX . 184In all cases, 185.Va errno 186is set to 187.Er ERANGE . 188If no conversion could be performed, 0 is returned and 189the global variable 190.Va errno 191is set to 192.Er EINVAL 193(the last feature is not portable across all platforms). 194.Sh ERRORS 195.Bl -tag -width Er 196.It Bq Er EINVAL 197The value of 198.Fa base 199is not supported or 200no conversion could be performed 201(the last feature is not portable across all platforms). 202.It Bq Er ERANGE 203The given string was out of range; the value converted has been clamped. 204.El 205.Sh SEE ALSO 206.Xr strtol 3 , 207.Xr strtonum 3 , 208.Xr wcstoul 3 209.Sh STANDARDS 210The 211.Fn strtoul 212function 213conforms to 214.St -isoC . 215The 216.Fn strtoull 217and 218.Fn strtoumax 219functions 220conform to 221.St -isoC-99 . 222The 223.Bx 224.Fn strtouq 225function is deprecated. 226