I was wondering why in C++ they say to use constant int instead of int when declaring an array size? What difference does it actually make in general?

Asked Sep 14 '22 at 13:21

Active Sep 14 '22 at 13:25

Viewed 51 times

EX:

const int SIZE = 10; 
int arr[SIZE];

int SIZE = 10; 
int arr[SIZE];

Even though the compiler doesn't seem to show any errors in the run time.

edited Sep 14 '22 at 13:22

Stack Danny

asked Sep 14 '22 at 13:21

2

In c++ array size must be constant expressions. Your second example is non standard c++ and should be avoided. – Hackjaku Sep 14 '22 at 13:23
1

When compiling use `-pedantic-errors`. Then you will get an error for the second code block. – NathanOliver Sep 14 '22 at 13:24
Visual Studio will show you an error if you try to compile the second version. gcc and clang unfortunately allow that by default. – Yksisarvinen Sep 14 '22 at 13:29
1

"The compiler" is wrong if it accepts that second code example without issuing a diagnostic. That is not valid C++. – Pete Becker Sep 14 '22 at 13:48

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