pvjc22/du1/program.c

#include <stdio.h>

int main(){
	int c = 1;
	char small[] = "abcdefghijklmnopqrstuvwxyz";
	char big[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
	while(c = 1){
		c = getchar();
		for(int i = 0; i < 26; i++){
			if(c == small[i]){
				c = big[i];
				break;
			}else if(c == big[i]){
				c = small[i];
				break;
			}
		}
	}
	return 0;
}