1.\" $NetBSD: strtol.3,v 1.40 2017/07/03 21:32:50 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: @(#)strtol.3 8.1 (Berkeley) 6/4/93 35.\" 36.Dd November 4, 2016 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 116or 117.Ql 0X 118prefix, 119and the number will be read in base 16; otherwise, 120.\" if the 121.\" .Fa base 122.\" is zero or 2, 123.\" the string may then include a 124.\" .Ql 0b 125.\" or 126.\" .Ql 0B 127.\" prefix, 128.\" and the number will be read in base 2; otherwise, 129a zero 130.Fa base 131is taken as 10 (decimal) unless the next character is 132.Ql 0 , 133in which case it is taken as 8 (octal). 134.Pp 135The remainder of the string is converted to an appropriate value 136in the obvious manner, 137stopping at the first character which is not a valid digit in the given base. 138(In bases above 10, the letter 139.Ql A 140in either upper or lower case 141represents 10, 142.Ql B 143represents 11, and so forth, with 144.Ql Z 145representing 35.) 146.Pp 147If 148.Fa endptr 149is non-nil, the functions store the address of the first invalid character in 150.Fa *endptr . 151If there were no digits at all, however, 152the functions store the original value of 153.Fa nptr 154in 155.Fa *endptr . 156(Thus, if 157.Fa *nptr 158is not 159.Ql \e0 160but 161.Fa **endptr 162is 163.Ql \e0 164on return, the entire string was valid.) 165.Sh RETURN VALUES 166The 167.Fn strtol 168function 169returns the result of the conversion, 170unless the value would underflow or overflow. 171If an underflow occurs, 172.Fn strtol 173returns 174.Dv LONG_MIN , 175.Fn strtoll 176returns 177.Dv LLONG_MIN , 178and 179.Fn strtoimax 180returns 181.Dv INTMAX_MIN . 182If an overflow occurs, 183.Fn strtol 184returns 185.Dv LONG_MAX , 186.Fn strtoll 187returns 188.Dv LLONG_MAX , 189and 190.Fn strtoimax 191returns 192.Dv INTMAX_MAX . 193In these cases, 194.Va errno 195is set to 196.Er ERANGE . 197If the 198.Fa base 199argument is not supported then 200.Va errno 201is set to 202.Er EINVAL 203and the functions return 0. 204.Pp 205If no error occurs, 206.Va errno 207is left unchanged. 208This behavior (which is unlike most library functions) is guaranteed 209by the pertinent standards. 210.Sh EXAMPLES 211Because the return value of 212.Fn strtol 213cannot be used unambiguously to detect an error, 214.Va errno 215is left unchanged after a successful call. 216To ensure that a string is a valid number (i.e., in range and containing no 217trailing characters), clear 218.Va errno 219beforehand explicitly, then check it afterwards: 220.Bd -literal -offset indent 221char *ep; 222long lval; 223 224\&... 225 226errno = 0; 227lval = strtol(buf, &ep, 10); 228if (ep == buf) 229 goto not_a_number; 230if (*ep != '\e0') 231 goto trailing_garbage; 232if (errno) { 233 assert(errno == ERANGE); 234 assert(lval == LONG_MAX || lval == LONG_MIN); 235 goto out_of_range; 236} 237.Ed 238.Pp 239This example will accept 240.Dq 12 241but not 242.Dq 12foo 243or 244.Dq 12\en . 245If trailing whitespace is acceptable, further checks must be done on 246.Va *ep ; 247alternately, use 248.Xr sscanf 3 . 249.Pp 250If 251.Fn strtol 252is being used instead of 253.Xr atoi 3 , 254error checking is further complicated because the desired return value is an 255.Li int 256rather than a 257.Li long ; 258however, on some architectures integers and long integers are the same size. 259Thus the following is necessary: 260.Bd -literal -offset indent 261char *ep; 262int ival; 263long lval; 264 265\&... 266 267errno = 0; 268lval = strtol(buf, &ep, 10); 269if (ep == buf) 270 goto not_a_number; 271if (*ep != '\e0') 272 goto trailing_garbage; 273if (errno == ERANGE || lval < INT_MIN || INT_MAX < lval) 274 goto out_of_range; 275assert(errno == 0); 276assert(INT_MIN <= lval); 277assert(lval <= INT_MAX); 278ival = lval; 279.Ed 280.Sh ERRORS 281.Bl -tag -width Er 282.It Bq Er EINVAL 283The 284.Ar base 285is not between 2 and 36 and does not contain the special value 0. 286.It Bq Er ERANGE 287The given string was out of range; the value converted has been clamped. 288.El 289.Sh SEE ALSO 290.Xr atof 3 , 291.Xr atoi 3 , 292.Xr atol 3 , 293.Xr atoll 3 , 294.Xr strtod 3 , 295.Xr strtou 3 , 296.Xr strtoul 3 , 297.Xr strtoull 3 , 298.Xr strtoumax 3 299.Sh STANDARDS 300The 301.Fn strtol 302function 303conforms to 304.St -ansiC . 305The 306.Fn strtoll 307and 308.Fn strtoimax 309functions conform to 310.St -isoC-99 . 311.Pp 312The 313.Fn strtoq 314function is a 315.Bx 316legacy function equivalent to 317.Fn strtoll 318and should not be used in a new code. 319.Sh BUGS 320Ignores the current locale. 321