codeup_100000569_D

解答：

#include <stdio.h>
#include <string.h>
int main() {
	char str[50];
	scanf("%s", str);
	for(int i = 0; i <= strlen(str)-1; i++) {
		//if(65 <= int(str[i]) && 90 >= int(str[i])) {
		if(str[i] >= 'A' && str[i] <= 'Z') {
			//printf("%c->", str[i]);
			str[i] = 155 - str[i];
			printf("%c", str[i]);
		}
		//else if(97 <= int(str[i]) && 122 >= int(str[i])) {
		else if(str[i] >= 'a' && str[i] <= 'z') {
			//printf("%c->", str[i]);
			str[i] = 219 - str[i];
			printf("%c", str[i]);
		}
		else
			printf("%c", str[i]); 
	}
	return 0;
}

总结：

声明字符数组时最好指定数组大小