Delimiting Char Array for Three Variables - c

Question

I'm writing a program to parse a command-line argument into three different parts: host name, file path, and file name, however I am unsure of how to parse a single command-line argument and store the separate parts in three different variables.
I need each portion to create a socket on the client-side of my program. So far I've been able to parse the host name portion, but I get stuck after that.
Is there a way that, after parsing a portion of the string?
EDIT:
The string I'm trying to parse is something like camelot.cba.csuohio.edu/~yourloginid/filename.txt
Here's my code
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
int main(int argc, char *argv[])
{
int i, sk;
char buf[256], temp[256];
struct sockaddr_in remote;
struct hostent *hp;
if(argc != 2)
{
printf("Invalid number of arguments. Program terminating...");
exit(1);
}
sk = socket(AF_INET, SOCK_STREAM, 0);
remote.sin_family = AF_INET;
strcpy(buf, argv[1]);
for(i = 0; i < strlen(buf); i++)
{
if(buf[i] == '/')
break;
temp[i] = buf[i];
}
hp = gethostbyname(temp);
return 0;
}
EDIT:
I've implemented a while loop to achieve what I'm looking for, but I feel like it's sloppy. Is there a way I can improve it?
while(tk != NULL)
{
if(c == 0)
strcpy(host, tk);
else if(c == 1)
strcpy(path, tk);
else
strcpy(fname, tk);
c++;
tk = strtok(NULL, "/");
}

Answer 1

char st[] = "camelot.cba.csuohio.edu/~yourloginid/filename.txt";
char *host, *path, *fname;
char *ch[3];
for (int i=0; i < 3; ++i) {
ch[i] = strtok(st, "/");
(if ch[i] == NULL) break;
printf("%s\n", ch[i]);
}
if (ch[0] != NULL) {
host = ch[0];
}
if (ch[1] != NULL) {
path = ch[1];
}
if (ch[2] != null) {
path = ch[2];
}
Output:
camelot.cba.csuohio.edu
~yourloginid
filename.txt

Answer 2

You can parse that with strtok
A rough example for you case would be
const char s[2] = "/";
char *token;
/* get the first token */
token = strtok(argv[1], s);
/* walk through other tokens */
while( token != NULL )
{
printf( " %s\n", token );
token = strtok(NULL, s);
}
I didn't compile it but I hope you can use it as an example.
Here you have a complete example of how to use it
http://www.tutorialspoint.com/c_standard_library/c_function_strtok.htm
Hope this helps.

Answer 3

When you know the delimiters, never forget you have simple pointer arithmetic available to you to split/parse any sting. strtok and sscanf are fine tools, but you can do the same thing manually. Here is a short example to add to your list:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAXS 128
int main (int argc, char **argv) {
if (argc < 2 ) {
fprintf (stderr, "Error: insufficient input, usage: %s host,path,file\n", argv[0]);
return 1;
}
char *line = strdup (argv[1]); /* make a copy of argument string */
if (!line) {
fprintf (stderr, "error: strdup memory allocation/copy failed.\n");
return 1;
}
char *p = line; /* pointer to the argument string */
char *sp = NULL; /* pointer to use as start pointer */
char host[MAXS] = {0}; /* variables to hold tokens */
char path[MAXS] = {0};
char file[MAXS] = {0};
while (*p && *p != ',') p++; /* find the first ',' */
*p++ = 0; /* null-terminate, advance pointer */
strcpy (host, line); /* read/copy host name */
sp = p; /* set start pointer at current pos */
while (*p && *p != ',') p++; /* find next ',' */
*p++ = 0; /* null-terminate, advance pointer */
strcpy (path, sp); /* read/copy path */
strcpy (file, p); /* pointer on file, read/copy file */
printf ("\n host: %s\n path: %s\n file: %s\n\n", host, path, file);
free (line); /* free memory allocate by strdup */
return 0;
}
Output
$ ./bin/split_host_path_file hostname,pathname,filename
host: hostname
path: pathname
file: filename
Updated to prevent potential read beyond end of line with p.

Answer 4

you can also parse with strtok_r as follows, since strtok is not thread safe.
const char *delim="/";
char *str, *savePtr;
char hosts[3][32];
int i;
for(i=0,str=strtok_r(argv[1], delim, &savePtr);(str!=NULL);str=strtok_r(NULL, delim, &savePtr), i++)
{
print("%s\n", str);
strcpy((char *)host[i], (const char *)str);
}
access host array elements, as it will contain the indexed values delimited by "/"