Using strtok in C language - c

Question

I have a problem using strtok in C. I get a user input from the command line using fgets and I want to tokenize it with pipe ("|") as the delimeter and put the result in a double pointer variable. Here's my code:
char** argv;
char *token;
token = strtok(userInput, "|");
while(token != NULL){
*(argv++) = token;
token = strtok(NULL, "|");
}
*argv = '\0';
I then use this code to verify if it's well tokenized
while(*argv!= NULL)
{
if((strcmp(*argv, "|") == 0){
count = count + 1;
}
argv++;
}
printf("%d pipes", count);
But it doesn't work. char** argv contains nothing. The execution of the code stops and it returns -1. When I try to print argv, argv contains no values.
Any ideas please? Thanks.
Edit:
What i want to do is this
userInput = "abc|cde";
After using strtok. I want to have an **argv
**argv = "abc";

Answer 1

One problem is that you don't seem to be initializing argv. You need to allocate enough memory for it to hold as many char *s as are needed. Otherwise you're writing to some random block of memory. (Is it just that you haven't shown us the relevant code?)
Another problem is that you're actually modifying argv, so at the end of that loop, it's pointing one past the last token (and then you set *argv to NULL); but your verification code assumes that it's pointing to the first token, and starts by confirming that *argv is not NULL. (Is it just that you haven't shown us some relevant code?) Edited to add: I see from your comment above that "argv contains no values". I'm pretty confident that this is the reason why.
Incidentally, you're confusing '\0' (a null byte) with NULL (a null pointer). Technically this works out correctly — '\0' gets promoted to 0, 0 gets converted to NULL — but I find it a bit worrisome that you're confusing them, since conceptually they are quite different. You should write *argv = NULL rather than *argv = '\0', for clarity if nothing else.

Answer 2

your tokenizing code works like this :
if
userInput = "a|b|c"
then
argv = { "a", "b", "c" }
you might be expecting that
argv = {"a","|","b","|","c"}
Your code to count pipes should be :
while(*argv != NULL)
{
count = count + 1;
argv++;
}
printf("%d pipes", count-1);
I think it will work

Answer 3

what I am using is this format for searching 300x400. looking for the "x" to get rid of the x and use both sides, the 300 and 400 . this works for me.
char *tok1, *tok2, *saveptr;
tok1 = strtok_r(argv, "x", &saveptr);
tok2 = strtok_r(NULL, "x", &saveptr);
printf("this tok1 %s this is tok2 %s\n", tok1, tok2);
using strtok_r function

Answer 4

the problem is your argv does not point to first element when you try to get result from it.
problem occurs here:
*(argv++) = token
argv (a pointer to char*) is increased when you add token pointer to argv array (I assume you have initialized it correctly). So when you use the second part of code to get the result, argv already points to the last element, in your case '\0', which will produce no output.
And, you are mixing '\0' with NULL, although they are both right grammatically, but it using NULL is better in your case, because it means a pointer, but '\0' means null-terminate in a C-string
You can change the your code to the following:
/* Init argv array */
char** argv;
size_t argc=0; // token count
char *token;
token = strtok(userInput, "|");
while(token != NULL){
argv[argc++] = token;
token = strtok(NULL, "|");
}
argv[argc] = NULL; // the last element of argv array is a NULL pointer
/* get result from argv */
while(*argv!= NULL)
{
if((strcmp(*argv, "|") == 0){
count = count + 1;
}
argv++;
}
printf("%d pipes", count);