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.Dd August 21, 2023 33.Dt STRTOUL 3 34.Os 35.Sh NAME 36.Nm strtoul , strtoull , strtoumax , strtouq 37.Nd "convert a string to an" 38.Vt "unsigned long" , "unsigned long long" , uintmax_t , 39or 40.Vt u_quad_t 41integer 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.In stdlib.h 46.In limits.h 47.Ft "unsigned long" 48.Fn strtoul "const char * restrict nptr" "char ** restrict endptr" "int base" 49.Ft "unsigned long long" 50.Fn strtoull "const char * restrict nptr" "char ** restrict endptr" "int base" 51.In inttypes.h 52.Ft uintmax_t 53.Fn strtoumax "const char * restrict nptr" "char ** restrict endptr" "int base" 54.In sys/types.h 55.In stdlib.h 56.In limits.h 57.Ft u_quad_t 58.Fn strtouq "const char *nptr" "char **endptr" "int base" 59.Sh DESCRIPTION 60The 61.Fn strtoul 62function 63converts the string in 64.Fa nptr 65to an 66.Vt "unsigned long" 67value. 68The 69.Fn strtoull 70function 71converts the string in 72.Fa nptr 73to an 74.Vt "unsigned long long" 75value. 76The 77.Fn strtoumax 78function 79converts the string in 80.Fa nptr 81to an 82.Vt uintmax_t 83value. 84The 85.Fn strtouq 86function 87converts the string in 88.Fa nptr 89to a 90.Vt u_quad_t 91value. 92The conversion is done according to the given 93.Fa base , 94which must be between 2 and 36 inclusive, 95or be the special value 0. 96.Pp 97The string may begin with an arbitrary amount of white space 98(as determined by 99.Xr isspace 3 ) 100followed by a single optional 101.Ql + 102or 103.Ql - 104sign. 105If 106.Fa base 107is zero or 16, 108the string may then include a 109.Dq Li 0b 110prefix, and the number will be read in base 2; or it may include a 111.Dq Li 0x 112prefix, 113and the number will be read in base 16; otherwise, a zero 114.Fa base 115is taken as 10 (decimal) unless the next character is 116.Ql 0 , 117in which case it is taken as 8 (octal). 118.Pp 119The remainder of the string is converted to an 120.Vt "unsigned long" 121value in the obvious manner, 122stopping at the end of the string 123or at the first character that does not produce a valid digit 124in the given base. 125(In bases above 10, the letter 126.Ql A 127in either upper or lower case 128represents 10, 129.Ql B 130represents 11, and so forth, with 131.Ql Z 132representing 35.) 133.Pp 134If 135.Fa endptr 136is not 137.Dv NULL , 138.Fn strtoul 139stores the address of the first invalid character in 140.Fa *endptr . 141If there were no digits at all, however, 142.Fn strtoul 143stores the original value of 144.Fa nptr 145in 146.Fa *endptr . 147(Thus, if 148.Fa *nptr 149is not 150.Ql \e0 151but 152.Fa **endptr 153is 154.Ql \e0 155on return, the entire string was valid.) 156.Sh RETURN VALUES 157The 158.Fn strtoul , 159.Fn strtoull , 160.Fn strtoumax 161and 162.Fn strtouq 163functions 164return either the result of the conversion 165or, if there was a leading minus sign, 166the negation of the result of the conversion, 167unless the original (non-negated) value would overflow; 168in the latter case, 169.Fn strtoul 170returns 171.Dv ULONG_MAX , 172.Fn strtoull 173returns 174.Dv ULLONG_MAX , 175.Fn strtoumax 176returns 177.Dv UINTMAX_MAX , 178and 179.Fn strtouq 180returns 181.Dv ULLONG_MAX . 182In all cases, 183.Va errno 184is set to 185.Er ERANGE . 186If no conversion could be performed, 0 is returned and 187the global variable 188.Va errno 189is set to 190.Er EINVAL 191(the last feature is not portable across all platforms). 192.Sh ERRORS 193.Bl -tag -width Er 194.It Bq Er EINVAL 195The value of 196.Fa base 197is not supported or 198no conversion could be performed 199(the last feature is not portable across all platforms). 200.It Bq Er ERANGE 201The given string was out of range; the value converted has been clamped. 202.El 203.Sh SEE ALSO 204.Xr strtol 3 , 205.Xr strtonum 3 , 206.Xr wcstoul 3 207.Sh STANDARDS 208The 209.Fn strtoul 210function 211conforms to 212.St -isoC . 213The 214.Fn strtoull 215and 216.Fn strtoumax 217functions 218conform to 219.St -isoC-99 . 220The 221.Bx 222.Fn strtouq 223function is deprecated. 224