Methodes

johand@osiris: ~/src/CCM/C $ cat powint.c 
#include <stdlib.h> 
#include <stdio.h> 

float powi(float base, int pow) 
{ 
  float res = 1.0; 
  float facteur = base; 
  if (pow < 0) 
    { 
      facteur = 1.0 / base; 
      pow = -pow; 
    } 
  while(pow) 
    { 
      if(pow & 1) 
 { 
   res = res * facteur; 
 } 
      facteur = facteur * facteur; 
      pow = pow >> 1; 
    } 
  return res; 
} 

int  main(int argc, char *argv[]) 
{ 
  float f; 
  int p; 
  if(argc >=3) 
    { 
      f = atof(argv[1]); 
      p = atoi(argv[2]); 
      printf("%f to the power %d is %f\n", f, p , powi(f, p)); 
      return EXIT_SUCCESS; 
    } 
  else 
    { 
      fprintf(stderr, "Usage is %s base power\n", argv[0]); 
      return EXIT_FAILURE; 
    } 
} 

    
johand@osiris: ~/src/CCM/C $ gcc -Wall -o powint powint.c 
johand@osiris: ~/src/CCM/C $ ./powint 5 -3 
5.000000 to the power -3 is 0.008000 
johand@osiris: ~/src/CCM/C $ ./powint 0.3 4 
0.300000 to the power 4 is 0.008100