using strtok splitting strings in c - c

Question

Hey I'm having problems with my code I get creating the tokens and have it adding it add the tokens to a 2d array but it doesn't work correctly. Any idea why.
/* strtok example */
#include <stdio.h>
#include <string.h>
int main ()
{
char str[] ="This a sample string";
char * st[4][0];
char * pch;
int i;
printf ("Splitting string \"%s\" into tokens:\n",str);
pch = strtok (str," ");
while (pch != NULL)
{
printf ("%s\n",pch);
pch = strtok (NULL, " ");
for(i=0;i<4;i++)
{
st[i][0]=pch;
}
}
print(st, i);
return 0;
}
void print(char st[4][0], int i)
{
for(i=0;i<4;i++)
{
printf("%d - %s",i ,st[i][0]);
}
}

Answer 1

char * st[4][0];
You are allocating an array of zero length. later you try to access the first element, which is non-existent, and therefore you get undefined behaviour.
I cannot see why this array has two dimensions anyway. You only access the first element of the second dimension, why not:
char * st[4];
??
To be more precise I don't understand the usage of this variable at all. Why do you write the same value in all four elements?

Answer 2

There are a number of problems: compare with this code:
/* strtok example */
#include <stdio.h>
#include <string.h>
void print(char *st[4]) // Fixed parameter type
{
int i; // i is a local counter
for(i=0;i<4;i++)
{
printf("%d - %s\n",i ,st[i]);
}
}
int main ()
{
char str[] ="This a sample string";
char * st[4]; // Corrected array definition
char * pch;
int i=0; // Initialise counter i to 0
printf ("Splitting string \"%s\" into tokens:\n",str);
pch = strtok (str," ");
while (pch != NULL)
{
st[i]=pch; // Store string before overwriting pch, and only store in a single location
printf ("%s\n",pch);
pch = strtok (NULL, " ");
i++; // increment i inside loop
}
print(st);
return 0;
}