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cloopstypesincompatibletypeerror

Incompatible types in assignment. C

This part of my code:

    char MAC_ADRESSES[MAX_LINES][100];
    for(j=i+1; j<=countlines; j++)
        {
            if((MAC_ADRESSES[j])==(MAC_ADRESSES[i]))
            {
                MAC_ADRESSES[j] = NULL;
            }

At the point where I want to change the string with a NULL I have a compiler error about incompatible types assignment. Do not understand why..

Solution

  • Presumably MAC_ADRESSES is not an array of pointers. NULL is a pointer (normally (void *)0 in C), so you can't assign it to a non-pointer variable.

    Edit: Since your definition is char MAC_ADRESSES[MAX_LINES][100], you have a 2D array, not an array of pointers. You can't store NULL in this array. You can wipe out a string by putting a null character in the first byte, though:

                MAC_ADRESSES[j][0] = '\0';

    Note that you can't test strings for equality using ==, either. You should be using strcmp.