Using const with pointer to array in formal parameter

Asked Jan 11 '18 at 14:50

Active Jan 11 '18 at 15:04

Viewed 86 times

I have a matrix data type and a function with a formal parameter of matrix type. Since the function will not modify its parameter I use a const qualifier:

typedef int Matrix[2][2];

static void Foo(const Matrix A)
{
    ...
}

When I call this function it seems like I need to cast the actual parameter:

Matrix A;
...
Foo((const int (*)[2]) A);

Without the cast the compiler I use (GCC) will issue a warning:

warning: pointers to arrays with different qualifiers are incompatible in ISO C [-Wpedantic]

Is there a different way to approach the problem so that the cast is not necessary?

edited Jan 11 '18 at 15:04

asked Jan 11 '18 at 14:50

August Karlstrom

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What's the exact error message? – Quentin Jan 11 '18 at 14:55
@Quentin See updated question. – August Karlstrom Jan 11 '18 at 15:05
Cannot [reproduce](http://coliru.stacked-crooked.com/a/688ca24e9d435bd5) – Jabberwocky Jan 11 '18 at 15:06
Do you have to strictly use gcc? I had no warnings compiling with g++ -Wall -Wextra -Wpedantic. – Jango Jan 11 '18 at 15:08
1

duplicate of [https://stackoverflow.com/questions/34488559/pointer-to-array-with-const-qualifier-in-c-c#34488782](https://stackoverflow.com/questions/34488559/pointer-to-array-with-const-qualifier-in-c-c#34488782) – Paul Götzinger Jan 11 '18 at 15:15
@MichaelWalz I use GCC 6.3.0 with the options `-Wall -pedantic -std=c89`. – August Karlstrom Jan 11 '18 at 16:54
@Jango I'm adhering to ANSI C89. Your command treats the code as C++. – August Karlstrom Jan 11 '18 at 17:04

Using const with pointer to array in formal parameter

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