My 2D Array in C is empty after populating it in a while loop, but within the loop it appears populated correctly

Question

I am new to C, and I'm trying to populate a 2D array by breaking a text file of instructions into sub-strings and storing them into it. This loop is to populate said Array, within the while loop, it prints perfectly fine and seems to store it correctly. After the while loop, the 2D array is now empty and I do not understand why.

I should not have to allocate memory from the Heap as this is all within the same function correct? If I'm wrong, please let me know what I should be doing instead, thank you.

My goal is to have an instruction like

mul 2 4

be stored into

instructionArr[0][0] = mul 
instructionArr[0][1] = 2 
instructionArr[0][2] = 4

Is this the correct way to even go about this?

char instruction[256];
char* instructionArr[100][5];

int line = 0;

while(fgets(instruction, 256, fp) != NULL) {

    printf("%s", instruction);

    char* tokenized = strtok(instruction, " ");

    int count = 0;

    while (tokenized != NULL) {

        printf("tokenized: line: %d, position: %d is: %s\n", line, count, tokenized);

        instructionArr[line][count] = tokenized;

        //Prints string correctly
        printf("tokenizedArr[%d][%d] = %s\n", line, count, instructionArr[line][count]);

        tokenized = strtok(NULL, " ");

        count ++;
    }

    line ++;
}

//Print the first element of instructionArr, [0][0], should be a string, but is nothing.
printf("tokenizedArr[%d][%d] = %s\n", 0, 0, instructionArr[0][0]);

Answer 1

strtok modifies the string it operates on. See https://wiki.sei.cmu.edu/confluence/display/c/STR06-C.+Do+not+assume+that+strtok%28%29+leaves+the+parse+string+unchanged

Also you should probably use strcpy() instead of "instructionArr[line][count] = tokenized;"

EDIT: strncpy() is safer