Question

I got 2 arrays :

data[256] = "1@2@3@4@5"
question[256][256];

I need to split the number before the @ into an array..
for example :

question[0][] = 1
question[1][] = 2
question[2][] = 3
question[3][] = 4
question[4][] = 5

It doesnt metter if I have the @ in, or not.

This is what I wrote :

int i = 0, j = 0;
 data = "1@2@3@4@5";

 for (i = 0 ; i < strlen(data) ; i++)
 {
     for (j ; data[j] != '@' ; j++)
     {
         question[i][j] = data[j];
     }
     j++
 }

 printf ("%s\n", question);

The problem is, it works untill the first @, and then stops.
It only put the first @ into question, and then stops.
(basiclly I’m supposed to get the same output for printing both data, and question).

Answer 1

There are a few problems.

First, printf only prints the string until the first terminating zero character ('\0'), which happens after the first “part” in question (even though there are other parts. Instead, you will need to print all:

for (i=0; i<255; ++i) {
  printf("%s\n", question[i]);
}

Make sure you null-terminate ('\0') the rows of question before, so you don’t print garbage for uninitialized rows. or just maintain the index of the last-good row and iterate until that

Also, the loop

for(j; data[j]!='@', j++)

will stop at the first '@', and all consequent iterations of the outside loop will evaluate the same j (which is the index of '@', so the loop is skipped in further iterations. You will need to advance j after the inner loop

you will also need to maintain a last-j position after the last '@' to be able to calculate the position of j from the last '@', so you can index into question[i] properly. set lastj to the value of j after is extra advancement suggested in the previous paragraph. Also, the second index of question should be j-lastj from now on.

Yet another thing about the inner loop: as it is, it will advance past the string in data after the last '@', so you will have to check for noll-termination as well.

Also, make sure you null-terminate the strings in question, otherwise printf will produce garbage (and possibly seg-fault when reaching memory not allocated to your progam). just write

question[i][j-lastj] = '\0';

after the inner loop. (j will have pointed after the last written index at the end of the inner loop)

Yet one more thing: do not iterate i until the length of data as you will not need to touch that many elements (and likely will overindex data in the inner loop). Use a while loop instead, incrementing i only until you have covered data with j in the inner loop

Note: look up strtok to make the tokenization easier on your part