1.\" $NetBSD: strtol.3,v 1.26 2009/07/23 13:38:57 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 July 23, 2009 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. 97The conversion is done according to the given 98.Fa base , 99which must be between 2 and 36 inclusive, 100or be the special value 0. 101.Pp 102The string may begin with an arbitrary amount of white space 103(as determined by 104.Xr isspace 3 ) 105followed by a single optional 106.Ql + 107or 108.Ql - 109sign. 110If 111.Fa base 112is zero or 16, 113the string may then include a 114.Ql 0x 115prefix, 116and the number will be read in base 16; otherwise, a zero 117.Fa base 118is taken as 10 (decimal) unless the next character is 119.Ql 0 , 120in which case it is taken as 8 (octal). 121.Pp 122The remainder of the string is converted to a 123.Em long 124value in the obvious manner, 125stopping at the first character which is not 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 non-nil, 139.Fn strtol 140stores the address of the first invalid character in 141.Fa *endptr . 142If there were no digits at all, however, 143.Fn strtol 144stores the original value of 145.Fa nptr 146in 147.Fa *endptr . 148(Thus, if 149.Fa *nptr 150is not 151.Ql \e0 152but 153.Fa **endptr 154is 155.Ql \e0 156on return, the entire string was valid.) 157.Sh RETURN VALUES 158The 159.Fn strtol 160function 161returns the result of the conversion, 162unless the value would underflow or overflow. 163If an underflow occurs, 164.Fn strtol 165returns 166.Dv LONG_MIN , 167.Fn strtoll 168returns 169.Dv LLONG_MIN , 170and 171.Fn strtoimax 172returns 173.Dv INTMAX_MIN . 174If an overflow occurs, 175.Fn strtol 176returns 177.Dv LONG_MAX , 178.Fn strtoll 179returns 180.Dv LLONG_MAX , 181and 182.Fn strtoimax 183returns 184.Dv INTMAX_MAX . 185In these cases, 186.Va errno 187is set to 188.Er ERANGE . 189If the 190.Fa base 191argument is not supported then 192.Va errno 193is set to 194.Er EINVAL 195and the functions return 0. 196.Pp 197If no error occurs, 198.Va errno 199is left unchanged. 200This behavior (which is unlike most library functions) is guaranteed 201by the pertinent standards. 202.Sh EXAMPLES 203Because the return value of 204.Fn strtol 205cannot be used unambiguously to detect an error, 206.Va errno 207is left unchanged after a successful call. 208To ensure that a string is a valid number (i.e., in range and containing no 209trailing characters), clear 210.Va errno 211beforehand explicitly, then check it afterwards: 212.Bd -literal -offset indent 213char *ep; 214long lval; 215 216\&... 217 218errno = 0; 219lval = strtol(buf, \*[Am]ep, 10); 220if (buf[0] == '\e0' || *ep != '\e0') 221 goto not_a_number; 222if (errno == ERANGE \*[Am]\*[Am] (lval == LONG_MAX || lval == LONG_MIN)) 223 goto out_of_range; 224.Ed 225.Pp 226This example will accept 227.Dq 12 228but not 229.Dq 12foo 230or 231.Dq 12\en . 232If trailing whitespace is acceptable, further checks must be done on 233.Va *ep ; 234alternately, use 235.Xr sscanf 3 . 236.Pp 237If 238.Fn strtol 239is being used instead of 240.Xr atoi 3 , 241error checking is further complicated because the desired return value is an 242.Li int 243rather than a 244.Li long ; 245however, on some architectures integers and long integers are the same size. 246Thus the following is necessary: 247.Bd -literal -offset indent 248char *ep; 249int ival; 250long lval; 251 252\&... 253 254errno = 0; 255lval = strtol(buf, \*[Am]ep, 10); 256if (buf[0] == '\e0' || *ep != '\e0') 257 goto not_a_number; 258if ((errno == ERANGE \*[Am]\*[Am] (lval == LONG_MAX || lval == LONG_MIN)) || 259 (lval \*[Gt] INT_MAX || lval \*[Lt] INT_MIN)) 260 goto out_of_range; 261ival = lval; 262.Ed 263.Sh ERRORS 264.Bl -tag -width Er 265.It Bq Er EINVAL 266The 267.Ar base 268is not between 2 and 36 and does not contain the special value 0. 269.It Bq Er ERANGE 270The given string was out of range; the value converted has been clamped. 271.El 272.Sh SEE ALSO 273.Xr atof 3 , 274.Xr atoi 3 , 275.Xr atol 3 , 276.Xr atoll 3 , 277.Xr strtod 3 , 278.Xr strtoul 3 , 279.Xr strtoull 3 , 280.Xr strtoumax 3 281.Sh STANDARDS 282The 283.Fn strtol 284function 285conforms to 286.St -ansiC . 287The 288.Fn strtoll 289and 290.Fn strtoimax 291functions conform to 292.St -isoC-99 . 293.Sh BUGS 294Ignores the current locale. 295