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c - pointer increment and dereference (lvalue required error)

I am trying to understand how pointer incrementing and dereferencing go together, and I did this to try it out:

#include <stdio.h>
int main(int argc, char *argv[])
{
    char *words[] = {"word1","word2"};
    printf("%p
",words);
    printf("%s
",*words++);
    printf("%p
",words);
    return 0;
}

I expected this code to do one of these:

  1. First dereference then increase the pointer (printing word1)
  2. First dereference then increase the value (printing ord1)
  3. Dereference pointer + 1 (printing word2)

But compiler won't even compile this, and gives this error: lvalue required as increment operand am I doing something wrong here?

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1 Answer

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by (71.8m points)

You need to put braces around the pointer dereference in the second printf, e.g.:printf("%s ",(*words)++); Also, if you're attempting to get number 2 in your list there, you need to use the prefix increment rather than postfix.


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