CODEWITHSUNDEEP
carrayspointers
Mani Sadhasivam
Mani Sadhasivam

Reputation: 53

What's wrong with increment operator in pointer array?

I just found a little confusion while using increment operator in pointer array.

Code 1:

int main(void) {
     char *array[] = {"howdy", "mani"};
     printf("%s", *(++array));
     return 0;
}

While compiling, gcc throws a well known error "lvalue required as increment operand".

But, when I compile the below code it shows no error!!! Why?

Code2:

int main(int argc, char *argv[]) {
     printf("%s",*(++argv));
     return 0;
}

In both cases, I have been incrementing an array of pointer. So, it should be done by this way.

char *array[] = {"howdy","mani"};
char **pointer = array;
printf("%s",*(++pointer));

But, why code2 shows no error?

Upvotes: 5

Views: 128

Answers (1)

M.M
M.M

Reputation: 141576

Arrays cannot be incremented.

In your first code sample you try to increment an array. In the second code sample you try to increment a pointer.

What's tripping you up is that when an array declarator appears in a function parameter list, it actually gets adjusted to be a pointer declarator. (This is different to array-pointer decay). In the second snippet, char *argv[] actually means char **argv.

See this thread for a similar discussion.

Upvotes: 5

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