1.\" $NetBSD: strtol.3,v 1.32 2015/05/01 14:17:56 christos 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: @(#)strtol.3 8.1 (Berkeley) 6/4/93 35.\" 36.Dd April 30, 2015 37.Dt STRTOL 3 38.Os 39.Sh NAME 40.Nm strtol , 41.Nm strtoll , 42.Nm strtoimax , 43.Nm strtoq 44.Nd convert string value to a long, long long, intmax_t or quad_t integer 45.Sh LIBRARY 46.Lb libc 47.Sh SYNOPSIS 48.In stdlib.h 49.In limits.h 50.Ft long int 51.Fn strtol "const char * restrict nptr" "char ** restrict endptr" "int base" 52.Ft long long int 53.Fn strtoll "const char * restrict nptr" "char ** restrict endptr" "int base" 54.Pp 55.In inttypes.h 56.Ft intmax_t 57.Fn strtoimax "const char * restrict nptr" "char ** restrict endptr" "int base" 58.Pp 59.In sys/types.h 60.In stdlib.h 61.In limits.h 62.Ft quad_t 63.Fn strtoq "const char * restrict nptr" "char ** restrict endptr" "int base" 64.Sh DESCRIPTION 65The 66.Fn strtol 67function 68converts the string in 69.Fa nptr 70to a 71.Ft long int 72value. 73The 74.Fn strtoll 75function 76converts the string in 77.Fa nptr 78to a 79.Ft long long int 80value. 81The 82.Fn strtoimax 83function 84converts the string in 85.Fa nptr 86to an 87.Ft intmax_t 88value. 89The 90.Fn strtoq 91function 92converts the string in 93.Fa nptr 94to a 95.Ft quad_t 96value. 97.Pp 98The conversion is done according to the given 99.Fa base , 100which must be between 2 and 36 inclusive, 101or be the special value 0. 102.Pp 103The string may begin with an arbitrary amount of white space 104(as determined by 105.Xr isspace 3 ) 106followed by a single optional 107.Ql + 108or 109.Ql - 110sign. 111If 112.Fa base 113is zero or 16, 114the string may then include a 115.Ql 0x 116prefix, 117and the number will be read in base 16; otherwise, a zero 118.Fa base 119is taken as 10 (decimal) unless the next character is 120.Ql 0 , 121in which case it is taken as 8 (octal). 122.Pp 123The remainder of the string is converted to an appropriate value 124in the obvious manner, 125stopping at the first character which is not a valid digit in the given base. 126(In bases above 10, the letter 127.Ql A 128in either upper or lower case 129represents 10, 130.Ql B 131represents 11, and so forth, with 132.Ql Z 133representing 35.) 134.Pp 135If 136.Fa endptr 137is non-nil, the functions store the address of the first invalid character in 138.Fa *endptr . 139If there were no digits at all, however, 140the functions store the original value of 141.Fa nptr 142in 143.Fa *endptr . 144(Thus, if 145.Fa *nptr 146is not 147.Ql \e0 148but 149.Fa **endptr 150is 151.Ql \e0 152on return, the entire string was valid.) 153.Sh RETURN VALUES 154The 155.Fn strtol 156function 157returns the result of the conversion, 158unless the value would underflow or overflow. 159If an underflow occurs, 160.Fn strtol 161returns 162.Dv LONG_MIN , 163.Fn strtoll 164returns 165.Dv LLONG_MIN , 166and 167.Fn strtoimax 168returns 169.Dv INTMAX_MIN . 170If an overflow occurs, 171.Fn strtol 172returns 173.Dv LONG_MAX , 174.Fn strtoll 175returns 176.Dv LLONG_MAX , 177and 178.Fn strtoimax 179returns 180.Dv INTMAX_MAX . 181In these cases, 182.Va errno 183is set to 184.Er ERANGE . 185If the 186.Fa base 187argument is not supported then 188.Va errno 189is set to 190.Er EINVAL 191and the functions return 0. 192.Pp 193If no error occurs, 194.Va errno 195is left unchanged. 196This behavior (which is unlike most library functions) is guaranteed 197by the pertinent standards. 198.Sh EXAMPLES 199Because the return value of 200.Fn strtol 201cannot be used unambiguously to detect an error, 202.Va errno 203is left unchanged after a successful call. 204To ensure that a string is a valid number (i.e., in range and containing no 205trailing characters), clear 206.Va errno 207beforehand explicitly, then check it afterwards: 208.Bd -literal -offset indent 209char *ep; 210long lval; 211 212\&... 213 214errno = 0; 215lval = strtol(buf, \*[Am]ep, 10); 216if (buf[0] == '\e0' || *ep != '\e0') 217 goto not_a_number; 218if (errno == ERANGE \*[Am]\*[Am] (lval == LONG_MAX || lval == LONG_MIN)) 219 goto out_of_range; 220.Ed 221.Pp 222This example will accept 223.Dq 12 224but not 225.Dq 12foo 226or 227.Dq 12\en . 228If trailing whitespace is acceptable, further checks must be done on 229.Va *ep ; 230alternately, use 231.Xr sscanf 3 . 232.Pp 233If 234.Fn strtol 235is being used instead of 236.Xr atoi 3 , 237error checking is further complicated because the desired return value is an 238.Li int 239rather than a 240.Li long ; 241however, on some architectures integers and long integers are the same size. 242Thus the following is necessary: 243.Bd -literal -offset indent 244char *ep; 245int ival; 246long lval; 247 248\&... 249 250errno = 0; 251lval = strtol(buf, \*[Am]ep, 10); 252if (buf[0] == '\e0' || *ep != '\e0') 253 goto not_a_number; 254if ((errno == ERANGE \*[Am]\*[Am] (lval == LONG_MAX || lval == LONG_MIN)) || 255 (lval \*[Gt] INT_MAX || lval \*[Lt] INT_MIN)) 256 goto out_of_range; 257ival = lval; 258.Ed 259.Sh ERRORS 260.Bl -tag -width Er 261.It Bq Er EINVAL 262The 263.Ar base 264is not between 2 and 36 and does not contain the special value 0. 265.It Bq Er ERANGE 266The given string was out of range; the value converted has been clamped. 267.El 268.Sh SEE ALSO 269.Xr atof 3 , 270.Xr atoi 3 , 271.Xr atol 3 , 272.Xr atoll 3 , 273.Xr strtod 3 , 274.Xr strtou 3 , 275.Xr strtoul 3 , 276.Xr strtoull 3 , 277.Xr strtoumax 3 278.Sh STANDARDS 279The 280.Fn strtol 281function 282conforms to 283.St -ansiC . 284The 285.Fn strtoll 286and 287.Fn strtoimax 288functions conform to 289.St -isoC-99 . 290.Pp 291The 292.Fn strtoq 293function is a 294.Bx 295legacy function equivalent to 296.Fn strtoll 297and should not be used in a new code. 298.Sh BUGS 299Ignores the current locale. 300