判斷一個整數是否是n^m次方類型數據，並比較乘法和除法性能差異

求取a = n^m 

#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>

int testnum(int num, int base)
{		
	if (num <= 0 || num < base || num % base != 0)
		return -1;
	if(num == base)
		return 1;
		
	num = num/base;
		 
	return num == 1 ? 1 : testnum(num, base);	
}


int testnummuti(int num, int base, int value)
{		
	if (num <= 0 || base <= 0 || value <= 0)
		return -1;
		
	if(num < base)
		return -1;	
	
	if(num == base)
		return 1;
			
	value *= base;
	if(value > num)
		return -1;
	
	return value == num ? 1 : testnummuti(num, base, value);	
}

int main(int argc, char **argv)
{
	int num;
	int base = 2;
	while(1){
		printf("please enter integer!\n");
		scanf("%d", &num);	
		
		if(num == 10)
			break;
		
		//int a = testnum(num, base);
		int a = testnummuti(1024, base, base);
		if(a == 1) {
			printf("OK!\n");
		} else {
			printf("FAILED!\n");
		}	
	}
	
	return 0;
}

反彙編發現其實 % 用的也是除法運算。