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From: Richard Harnden <richard.nospam@gmail.invalid>
Newsgroups: comp.lang.c
Subject: enums and switch vs function calls
Date: Sat, 5 Apr 2025 11:29:41 +0100
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If I have:

enum colour {RED, GREEN, BLUE}

int colour_to_hex(enum colour colour)
{
     switch (colour)
     {
         RED: return 0xff0000;
         GREEN: return 0x00ff00;
         // BLUE: return 0x0000ff;
     }

     ...
}

.... then the compiler will warn me that I've missed a case in the switch 
statement.  Which is good and very helpful.

But if I do:

int hex = colour_to_hex(10);

.... then the compiler doesn't complain that 10 is not in the enum.

Why? Surely the compiler can tell.