Tokenizing strings in C

I have been trying to tokenize a string using SPACE as delimiter but it doesn't work. Does any one have suggestion on why it doesn't work?

Edit: tokenizing using:

strtok(string, " ");

The code is like the following

pch = strtok (str," ");
while (pch != NULL)
{
  printf ("%s\n",pch);
  pch = strtok (NULL, " ");
}

Do it like this:

char s[256];
strcpy(s, "one two three");
char* token = strtok(s, " ");
while (token) {
    printf("token: %s\n", token);
    token = strtok(NULL, " ");
}

Note: strtok modifies the string its tokenising, so it cannot be a const char*.

Here's an example of strtok usage, keep in mind that strtok is destructive of its input string (and therefore can't ever be used on a string constant

char *p = strtok(str, " ");
while(p != NULL) {
    printf("%s\n", p);
    p = strtok(NULL, " ");
}

Basically the thing to note is that passing a NULL as the first parameter to strtok tells it to get the next token from the string it was previously tokenizing.