Array code Compile error[c]

Question

Can anyone tell me whats the problem with this code and how Can I fix it? (Compile error) thank you! :)

#include <stdio.h>

int[] initArray(int arr[]);
void printArray(int arr[]);

 int main()
 {
      int myGrades[2];
      myGrades = initArray(myGrades);
      printArray(myGrades);
      return (0);
 }

 int[] initArray(int arr[])
 {
      arr[0] = 78;
      arr[1] = 86;
      return arr; 
 }

 void printArray(int arr[])
 {
     printf("My grade in English is: %d!\n",arr[0]);
     printf("My grade in History is %d! What an achievement!\n",arr[1]);
 }

Are you sure you need this to write `int[] initArray(int arr[]`? — Michi, Jan 09 '16 at 12:24
it's long time i didn't had any thing to do with C++. but i remember once i wanted to use it in VS, and some specific project type, i had to use the "using std" or something similar import, and it had it's own order ...here found it: `using namespace std` i'm not sure what kind of error you receive that i be able to help you, but take a look at this one — Hassan Faghihi, Jan 09 '16 at 12:33
@deadManN: that's terrible advice even if the question was about C++. If that's all you remember, better forget that too. — Mat, Jan 09 '16 at 12:36
Is there another way without using Pointers? never knew Pointers and I do not understand it — NoNameP, Jan 09 '16 at 12:40
If you don't understand pointers or you never learned them, Why do you still learn the Language ? — Michi, Jan 09 '16 at 12:45
[Try This](http://ideone.com/NWgUkB) and also [This](http://ideone.com/1zKM6U) and read iharob Answer — Michi, Jan 09 '16 at 12:47
@Mat :D sorry then, cause i didn't see any thing wrong with his program, (the way i remember it), again sorry — Hassan Faghihi, Jan 09 '16 at 14:06

Iharob Al Asimi · Accepted Answer · 2016-01-09T12:57:07.323

1

You cannot assign to arrays in c, so this
```
int myGrades[2];
myGrades = initArray(myGrades);
```
is invalid, you simply cannot assign to an array but passing the array as a parameter should modify it inside the function as a pointer to the first element of the array is really passed, see the next point to understand why.

To fix this part, just remove the assignment
```
initArray(myGrades);
```
is enough.

You cannot define a function like this

int[] initArray(int arr[])
{
     arr[0] = 78;
     arr[1] = 86;
     return arr; 
}

Quoting this document, the C11 Standard Draft

6.7.6.3 Function declarators (including prototypes)

A function declarator shall not specify a return type that is a function type or an array type.

The [] syntax cannot be used for a function return type, also as a function parameter it will become a int poitner anyway so using int arr[] can be misleading, for example you can try to apply the sizeof operator to it, and it will give you the size of a pointer.

Change it to

    void initArray(int *arr)
    {
         arr[0] = 78;
         arr[1] = 86;
    }

and it should compile.

Although, the returned pointer is only valid in the scope where you defined arr, in your program it's valid in main() so pretty much everywhere if you pass arr as a parameter to any function it will be fine. The point is that you don't need to return it at all since the original array (the one you passed to the function) is altered in place.

edited Jan 09 '16 at 12:57

answered Jan 09 '16 at 12:22

Iharob Al Asimi

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By making that change will make `myGrades = initArray(myGrades);` to be `incompatible types when assigning to type ‘int[2]’ from type ‘int *’|` – Michi Jan 09 '16 at 12:27
@Michi it's invalid already. – Iharob Al Asimi Jan 09 '16 at 12:29
I know and i didn't down voted you by the way :D – Michi Jan 09 '16 at 12:32
But now I understand why the downvote, I completely missed that! – Iharob Al Asimi Jan 09 '16 at 12:33
Is there another way without using Pointers? never knew Pointers and I do not understand it – NoNameP Jan 09 '16 at 12:40
You can't because once you pass the array as a parameter it's already a pointer. You don't have to deal with it and that means that you should not care if it's a pointer. BUT YOU CAN NEVER ASSIGN TO AN ARRAY. – Iharob Al Asimi Jan 09 '16 at 12:42
There is no need for `int *initArray(int *arr)` in his program `void initArray(int *arr)` and removing the return statement will be enough. – Michi Jan 09 '16 at 12:56
@NoNameP If you really need to avoid Pointer notation (instead of `*arr` just use `arr[]`), then you [need something like this](http://ideone.com/D6OKCG). But you should know, that `arr[]` used as function argument is a pointer. – Michi Jan 09 '16 at 13:00
@Michi Im trying the code but I have a Compile error in the last line("sytax error at end of input") What I need to do to fix it? – NoNameP Jan 09 '16 at 13:08
Copy and paste the whole code. – Michi Jan 09 '16 at 13:09
I did it but still have – NoNameP Jan 09 '16 at 13:09
Thank you very much @iharob – NoNameP Jan 09 '16 at 13:14

Array code Compile error[c]

1 Answers1