Function in C

Question

Hello!

I'm sorry, but I newbie in C, and I don't understand why I need to declare empty function at first and in the end of code I need to declare function with attributes, like this:

   int funky_math(int a, int b);
   int main()
   {
       int foo = 24;
       int bar = 35;
       int result = funky_math(foo, bar);
       printf("funky math %d\n", result);
       return 0;
   }

   int funky_math(int a, int b) {
       return a + b + 123;
   }

Why I can't write:

   int funky_math(int a, int b) {
       return a + b + 123;
   }
   int main()
   {

       int foo = 24;
       int bar = 35;
       int result = funky_math(foo, bar);
       printf("funky math %d\n", result);
       return 0;
   }

? Thank you for your help and sorry for my English:)

Answer 1 · 2013-12-07T17:41:00Z

December 7, 2013 5:41pm

You can write either however the first approach is recommended. Imagine a complex C program where you need to split functions up into multiple files. You can create a header file that contains only the definition of functions and a separate implementation file. When compiling the compiler just needs to include the header file which would be small. However, if you do not split up the header and implementation then the compiler would need to include all the implementation details which are not needed.

Answer 2 · 2013-12-07T19:49:09Z

December 7, 2013 7:49pm

Thank you, Amit! I'll try to learn more:)

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Alexander Bakushkin

Alexander Bakushkin

Function in C

2 Answers

Amit Bijlani

Amit Bijlani

Alexander Bakushkin

Alexander Bakushkin