1.\" $NetBSD: strtol.3,v 1.20 2003/04/16 13:34:47 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. All advertising materials mentioning features or use of this software 19.\" must display the following acknowledgement: 20.\" This product includes software developed by the University of 21.\" California, Berkeley and its contributors. 22.\" 4. Neither the name of the University nor the names of its contributors 23.\" may be used to endorse or promote products derived from this software 24.\" without specific prior written permission. 25.\" 26.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36.\" SUCH DAMAGE. 37.\" 38.\" from: @(#)strtol.3 8.1 (Berkeley) 6/4/93 39.\" 40.Dd August 11, 2002 41.Dt STRTOL 3 42.Os 43.Sh NAME 44.Nm strtol , 45.Nm strtoll , 46.Nm strtoimax , 47.Nm strtoq 48.Nd "convert string value to a long, long long, intmax_t or quad_t integer" 49.Sh LIBRARY 50.Lb libc 51.Sh SYNOPSIS 52.In stdlib.h 53.In limits.h 54.Ft long int 55.Fn strtol "const char * restrict nptr" "char ** restrict endptr" "int base" 56.Ft long long int 57.Fn strtoll "const char * restrict nptr" "char ** restrict endptr" "int base" 58.Pp 59.In inttypes.h 60.Ft intmax_t 61.Fn strtoimax "const char * restrict nptr" "char ** restrict endptr" "int base" 62.Pp 63.In sys/types.h 64.In stdlib.h 65.In limits.h 66.Ft quad_t 67.Fn strtoq "const char * restrict nptr" "char ** restrict endptr" "int base" 68.Sh DESCRIPTION 69The 70.Fn strtol 71function 72converts the string in 73.Fa nptr 74to a 75.Em long int 76value. 77The 78.Fn strtoll 79function 80converts the string in 81.Fa nptr 82to a 83.Em long long int 84value. 85The 86.Fn strtoimax 87function 88converts the string in 89.Fa nptr 90to an 91.Em intmax_t 92value. 93The 94.Fn strtoq 95function 96converts the string in 97.Fa nptr 98to a 99.Em quad_t 100value. 101The conversion is done according to the given 102.Fa base , 103which must be between 2 and 36 inclusive, 104or be the special value 0. 105.Pp 106The string may begin with an arbitrary amount of white space 107(as determined by 108.Xr isspace 3 ) 109followed by a single optional 110.Ql + 111or 112.Ql - 113sign. 114If 115.Fa base 116is zero or 16, 117the string may then include a 118.Ql 0x 119prefix, 120and the number will be read in base 16; otherwise, a zero 121.Fa base 122is taken as 10 (decimal) unless the next character is 123.Ql 0 , 124in which case it is taken as 8 (octal). 125.Pp 126The remainder of the string is converted to a 127.Em long 128value in the obvious manner, 129stopping at the first character which is not a valid digit 130in the given base. 131(In bases above 10, the letter 132.Ql A 133in either upper or lower case 134represents 10, 135.Ql B 136represents 11, and so forth, with 137.Ql Z 138representing 35.) 139.Pp 140If 141.Fa endptr 142is non nil, 143.Fn strtol 144stores the address of the first invalid character in 145.Fa *endptr . 146If there were no digits at all, however, 147.Fn strtol 148stores the original value of 149.Fa nptr 150in 151.Fa *endptr . 152(Thus, if 153.Fa *nptr 154is not 155.Ql \e0 156but 157.Fa **endptr 158is 159.Ql \e0 160on return, the entire string was valid.) 161.Sh RETURN VALUES 162The 163.Fn strtol 164function 165returns the result of the conversion, 166unless the value would underflow or overflow. 167If an underflow occurs, 168.Fn strtol 169returns 170.Dv LONG_MIN , 171.Fn strtoll 172returns 173.Dv LLONG_MIN , 174and 175.Fn strtoimax 176returns 177.Dv INTMAX_MIN . 178If an overflow occurs, 179.Fn strtol 180returns 181.Dv LONG_MAX , 182.Fn strtoll 183returns 184.Dv LLONG_MAX , 185and 186.Fn strtoimax 187returns 188.Dv INTMAX_MAX . 189In these cases, 190.Va errno 191is set to 192.Er ERANGE . 193.Sh EXAMPLES 194Ensuring that a string is a valid number (i.e., in range and containing no 195trailing characters) requires clearing 196.Va errno 197beforehand explicitly since 198.Va errno 199is not changed on a successful call to 200.Fn strtol , 201and the return value of 202.Fn strtol 203cannot be used unambiguously to signal an error: 204.Bd -literal -offset indent 205char *ep; 206long lval; 207 208\&... 209 210errno = 0; 211lval = strtol(buf, &ep, 10); 212if (buf[0] == '\e0' || *ep != '\e0') 213 goto not_a_number; 214if (errno == ERANGE && (lval == LONG_MAX || lval == LONG_MIN)) 215 goto out_of_range; 216.Ed 217.Pp 218This example will accept 219.Dq 12 220but not 221.Dq 12foo 222or 223.Dq 12\en . 224If trailing whitespace is acceptable, further checks must be done on 225.Va *ep ; 226alternately, use 227.Xr sscanf 3 . 228.Pp 229If 230.Fn strtol 231is being used instead of 232.Xr atoi 3 , 233error checking is further complicated because the desired return value is an 234.Li int 235rather than a 236.Li long ; 237however, on some architectures integers and long integers are the same size. 238Thus the following is necessary: 239.Bd -literal -offset indent 240char *ep; 241int ival; 242long lval; 243 244\&... 245 246errno = 0; 247lval = strtol(buf, &ep, 10); 248if (buf[0] == '\e0' || *ep != '\e0') 249 goto not_a_number; 250if ((errno == ERANGE && (lval == LONG_MAX || lval == LONG_MIN)) || 251 (lval > INT_MAX || lval < INT_MIN)) 252 goto out_of_range; 253ival = lval; 254.Ed 255.Sh ERRORS 256.Bl -tag -width Er 257.It Bq Er ERANGE 258The given string was out of range; the value converted has been clamped. 259.El 260.Sh SEE ALSO 261.Xr atof 3 , 262.Xr atoi 3 , 263.Xr atol 3 , 264.Xr atoll 3 , 265.Xr strtod 3 , 266.Xr strtoul 3 , 267.Xr strtoull 3 , 268.Xr strtoumax 3 269.Sh STANDARDS 270The 271.Fn strtol 272function 273conforms to 274.St -ansiC . 275The 276.Fn strtoll 277and 278.Fn strtoimax 279functions conform to 280.St -isoC99 . 281.Sh BUGS 282Ignores the current locale. 283