Code

 Header...
// Demonstrate prototypes and local variables 

// Function prototype
double mypow (double base,int exponent);

 int main(){
   ... 

»  double base=2;
»  int exponent=3;
»  double pow1, pow2;
 
»  pow1=mypow(2.0, 3);
»  pow2=mypow(base, exponent);// Surely the computer will take the hint!

»  printf("power is %f, exponent is %d\n", pow2, exponent);
}

//
// Return base to the power of exponent. 
// If base == zero and exponent < zero, 
// print a warning and return zero
//
 double mypow(double base,int exponent){
   ... 

»  double result=1.0;

»  if (base==0.0&&exponent<0) {// Or fabs(base) < 1e-50
»    printf("WARNING: mypow called with zero base and negative exponent\n");
»    return 0.0;
  }

»  while (exponent>0) {
»    result*=base;
»    --exponent;
  }
  
»  while (exponent<0) {
»    result/=base;
»    ++exponent;
  }
  
»  return result;
}

Data