08/01/21 13:13:09
>>387の修正版
#include<stdio.h>
long get_power(long base, int expt);
int main(int argc, char *argv[]){
int base, expt;
long power_out;
if(argc != 3){
fprintf(stderr, "input error\n");
return 1;
}
base = atoi(argv[1]);
expt = atoi(argv[2]);
if(expt < 0){
fprintf(stderr, "input error\n");
return 1;
}
power_out = get_power(base, expt);
printf("%d^%d = %ld\n", base, expt, power_out);
return 0;
}
long get_power(long base, int expt){
if(expt == 0) return 1;
if(expt % 2 == 0){
expt /= 2;
base *= base;
return get_power(base, expt);
}else{
expt -= 1;
return base * get_power(base, expt);
}
}