Why doesn't this C program compile? What is wrong with this?

Question

Why doesn't this C program compile? What is wrong with this?

I have tried it on wxDevC++ and Turbo C++ 3.0.

Main.c

#include<stdio.h>
#include<conio.h>

const int SIZE = 5;

int main(int argc, char ** argv)
{    
    char array[SIZE] = {'A', 'B', 'C', 'D', 'E'};

    printf("Array elements are,\n");
    int i=0;

    for(i=0 ; i<SIZE ; ++i)
    {
        printf("%c  ", array[i]);
    }

    getch();

    return 0;
}

Error Messages on the both of the compilers are similar.

f:\_Source-Codes\main.c In function `main':

8 f:\_Source-Codes\main.c variable-sized object may not be initialized

Answer 1

if the compiler is treating it as a '.c' file, the int i declaration needs to before any executable lines, speficically, before the printf.

EDIT, now that you showed the error message:

The compiler does not consider SIZE as a constant when compiling main. You could use #define SIZE 5 as a work-around.

According to K&R 2nd Ed. :

"The purpose of const is to announce objects that may be placed in read-only memory. ... Except that it should diagnose explicit attempts to change const objects, a compiler may ignore [the const] qualifier".

So declaring const int SIZE = 5 does not make SIZE a constant-expression, which is what an array size specifier requires.

Answer 2

try this:

char array[] = {'A', 'B', 'C', 'D', 'E'};

Answer 3

Try replacing

const int SIZE = 5;

with

#define SIZE 5

Most C compilers don't allow declaring static arrays whose sizes are contained in variables (i.e. the array size is determined at runtime).

Answer 4

Array size in C89/90 language must be specified by an integral constant expression (in general true for C99 as well). A const int object in C is not a constant expression, which is why you can't use it to specify array size. Note: this is one prominent difference between C and C++.

In C language the term constant refers to literal constants, i.e. 5, 10.2, 0xFF, 'a' and so on (enum constants are also constants, to be precise). const int object, once again, is not a constant in C and cannot be used to build constant expressions.

If you want to pre-declare a named constant to be used as array size in C, you have to use either #define or enum. The same applies to case labels, bit-field sizes and every other context requiring a constant expression.

See this for more details.