Thread: HELP...Use strtok to store strings in global variables...

Hello, my name is Estella. I have a question about using strtok() to store strings in global variables... because I got quite stuck in my functions...

I declared global variables:

Code:

// Global variable
char *namePtr[100] = {0}; 
int n;  /*number of components*/

I wrote a function eat_path to split a string into components:
e.g. /a/b/c => namePtr[0] = a, namePtr[1] = b, namePtr[2] = c

In eat_part function:

Code:

void eat_path(char *pathname)
{
printf("Enter eat_path\n");
//eat_path() breaks up a pathname into component strings.
//Example : pathname = /this/is/a/test
//Then n=4, namePtr[0] ="this", namePtr[1] ="is", namePtr[2] ="a", 
//namePtr[3] ="test" 
//The component names will be used to search for a child under its
parent
char path[40];
char delim[] = "/"; /* delimiter is '/' */
int i = 0, j = 0;

strcpy(path, pathname);

namePtr[j++] = strtok( path, delim );

while(namePtr[j++] = strtok( NULL,delim ));

j--;

n = j;

printf("\nNumber of components: %d\n", n);

for(i = 0; i < n; i++)
{
printf("%d %s\n", i, namePtr[i]);
}
printf("eat_path ends\n");
}

It works fine when I printed the namePtr inside this function, but
when I print namePtr in another function. it prints out garbage...

This is another function that calls eat_path:

Code:

NODE *namei(char *pathname)
{
NODE *ret; 
int i = 0;

//namei() returns the node pointer of a pathname, or 0;
//First, call eat_path() to break up pathname into component strings.
printf("In namei(), pathname = %s\n", pathname);
eat_path(pathname);
printf("After eat_path: In namei(), pathname = %s\n", pathname);
for(int j = 0; j < n; j++)
printf("%d %s\n", j, namePtr[j]);
//For each component string, call search_child() to look for the
child
//under its parent.
if (pathname[0] == '/')
ret = root;
else
ret = cwd;

while (ret != 0 && i < n)
{
//printf("namePtr[%d] = %s\n", i, namePtr[i]);
ret = search_child(ret, namePtr[i]);
i++;
}
return ret;
}

I checked the content of namePtr right after calling eat_path, so the
namePtr should contain the same thing when the program is still inside
eat_path...
I am so lost... thank you for helping..

Oh, the joys of global pointers referencing local variables from a different scope than they were declared in. When eat_path returns, path doesn't exist anymore, so your pointers are dangling. You would be better off making a copy of pathname in the calling function and passing that to eat_path rather than making the copy in eat_path.