Xcode - Warning: Implicit declaration of function is invalid in C99

Question

Getting a warning : Implicit declaration of function \'Fibonacci\' is invalid in C99. What\'s wrong?

#include 

int main(int argc, const char          


        

Answer 1

The compiler wants to know the function before it can use it

just declare the function before you call it

#include 

int Fibonacci(int number); //now the compiler knows, what the signature looks like. this is all it needs for now

int main(int argc, const char * argv[])
{
    int input;
    printf("Please give me a number : ");
    scanf("%d", &input);
    getchar();
    printf("The fibonacci number of %d is : %d", input, Fibonacci(input)); //!!!

}/* main */

int Fibonacci(int number)
{
//…