pvjc22/du1/program.c

#include <stdio.h>

int main(){
	int c = 0;
	int a = 0;
	char small[] = "abcdefghijklmnopqrstuvwxyz";
    	char big[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
	char d;
	while( c != EOF){
		c = getchar();
		d = c;
		int a = 0;
		while(a > 26){
			if(d == small[a]){
				c = big[a];
				break;
			}else if(d == big[a]){
				c = small[a];
				break;
			}		
		}
		putchar (c);
	}
	return 0;
}