reverse.c

#include<stdio.h>
#include<string.h>

void swap(char *c1, char *c2){
	*c1 ^= *c2 ^= *c1 ^= *c2;
}

/* 想法 */
char *reverse_iterative(char *s){
	int len = strlen(s);
	int i;
	for ( i = 0; i < len / 2; i++){
		swap(s+i, s+(len-1-i));
	}
	return s;
}



char *reverse_recursive(char *s){
	static int time = 0;
    	static int len = 0;
	
	if (time == 0){
		len = strlen(s);
	}
	if (time == len / 2){
		return s;
	}

	swap(s+time, s+len-1-time);
	time += 1;
	return reverse_recursive(s);

}


int main(){
	char str[10] = "hello";
//	printf("%s\n", reverse_iterative(str));
	reverse_recursive(str);
	printf("%s\n", 	reverse_recursive(str));
	return 0;
}