I just wrote a program in C to split a comma seperated string in to group of strings using strtok() function. The code is:
The program compiles without error(please bear any syntax error, since i typed in hand without the code with me but the orignial program compiles successfully) but i am getting runtime error like 'Segmentation Fault'. I hope there needs to be proper memory handling here which i am not sure of.
Please help me in getting this splitted set of strings to a new 2-D array.
Thanks in advance.
Hi,
Just a little comment after a quick look to your code: i would suggest you to allocate memory properly (using malloc) and not use a shortcut like this
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I will start with an example of what I'm trying to do and then describe how I am approaching the issue.
File
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Lexeme HRS # M #
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Discussion started by: jvoot
17 Replies
LEARN ABOUT DEBIAN
strtok
STRTOK(3) Linux Programmer's Manual STRTOK(3)NAME
strtok, strtok_r - extract tokens from strings
SYNOPSIS
#include <string.h>
char *strtok(char *str, const char *delim);
char *strtok_r(char *str, const char *delim, char **saveptr);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
strtok_r(): _SVID_SOURCE || _BSD_SOURCE || _POSIX_C_SOURCE >= 1 || _XOPEN_SOURCE || _POSIX_SOURCE
DESCRIPTION
The strtok() function parses a string into a sequence of tokens. On the first call to strtok() the string to be parsed should be specified
in str. In each subsequent call that should parse the same string, str should be NULL.
The delim argument specifies a set of bytes that delimit the tokens in the parsed string. The caller may specify different strings in
delim in successive calls that parse the same string.
Each call to strtok() returns a pointer to a null-terminated string containing the next token. This string does not include the delimiting
byte. If no more tokens are found, strtok() returns NULL.
A sequence of two or more contiguous delimiter bytes in the parsed string is considered to be a single delimiter. Delimiter bytes at the
start or end of the string are ignored. Put another way: the tokens returned by strtok() are always nonempty strings.
The strtok_r() function is a reentrant version strtok(). The saveptr argument is a pointer to a char * variable that is used internally by
strtok_r() in order to maintain context between successive calls that parse the same string.
On the first call to strtok_r(), str should point to the string to be parsed, and the value of saveptr is ignored. In subsequent calls,
str should be NULL, and saveptr should be unchanged since the previous call.
Different strings may be parsed concurrently using sequences of calls to strtok_r() that specify different saveptr arguments.
RETURN VALUE
The strtok() and strtok_r() functions return a pointer to the next token, or NULL if there are no more tokens.
CONFORMING TO
strtok()
SVr4, POSIX.1-2001, 4.3BSD, C89, C99.
strtok_r()
POSIX.1-2001.
BUGS
Be cautious when using these functions. If you do use them, note that:
* These functions modify their first argument.
* These functions cannot be used on constant strings.
* The identity of the delimiting byte is lost.
* The strtok() function uses a static buffer while parsing, so it's not thread safe. Use strtok_r() if this matters to you.
EXAMPLE
The program below uses nested loops that employ strtok_r() to break a string into a two-level hierarchy of tokens. The first command-line
argument specifies the string to be parsed. The second argument specifies the delimiter byte(s) to be used to separate that string into
"major" tokens. The third argument specifies the delimiter byte(s) to be used to separate the "major" tokens into subtokens.
An example of the output produced by this program is the following:
$ ./a.out 'a/bbb///cc;xxx:yyy:' ':;' '/'
1: a/bbb///cc
--> a
--> bbb
--> cc
2: xxx
--> xxx
3: yyy
--> yyy
Program source
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int
main(int argc, char *argv[])
{
char *str1, *str2, *token, *subtoken;
char *saveptr1, *saveptr2;
int j;
if (argc != 4) {
fprintf(stderr, "Usage: %s string delim subdelim
",
argv[0]);
exit(EXIT_FAILURE);
}
for (j = 1, str1 = argv[1]; ; j++, str1 = NULL) {
token = strtok_r(str1, argv[2], &saveptr1);
if (token == NULL)
break;
printf("%d: %s
", j, token);
for (str2 = token; ; str2 = NULL) {
subtoken = strtok_r(str2, argv[3], &saveptr2);
if (subtoken == NULL)
break;
printf(" --> %s
", subtoken);
}
}
exit(EXIT_SUCCESS);
}
Another example program using strtok() can be found in getaddrinfo_a(3).
SEE ALSO index(3), memchr(3), rindex(3), strchr(3), string(3), strpbrk(3), strsep(3), strspn(3), strstr(3), wcstok(3)COLOPHON
This page is part of release 3.44 of the Linux man-pages project. A description of the project, and information about reporting bugs, can
be found at http://www.kernel.org/doc/man-pages/.
GNU 2012-05-10 STRTOK(3)