Why do I get clang: error: linker command failed with exit code 1?

Why do I get clang: error: linker command failed with exit code 1?

You just declared the function. There is not any definition in code. At the time of linking process , compiler(here clang) cannot link power function to its definition so linker throws the error in this kind of situation. If you define

int power(int x, int y)  
         { 
               \*do calculation*/
         }

Then linker can link your declaration of power function to its definition ,you will not get any error.

For integer number I have made function for you.

#include <stdio.h>
int power(int base, int exp);
int main()
{
int i;

for (i=0; i<10; ++i)
    printf("%d %d %d\n", i, power(2,i), power(-3,i));

return 0;
}

int power(int base, int exp)
{
    int result = 1;
    while (exp)
    {
        if (exp & 1)
            result *= base;
        exp >>= 1;
        base *= base;
    }

    return result;
}

Compile this with gcc file.c

Hope you understand the function. Good luck 🙂