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

void invert(char s[]) 
{
	int anz = 'a' - 'A';
	int i;
	
	for (i = 0; i < strlen(s); i++) 
	{
		int c = s[i];
		
		if (isupper(c)) 
			c = c + anz;
		else if (islower(c)) 
			c = c - anz;
		s[i] = c;
	}
}

void reverse(char s[]) 
{
	int l = strlen(s);
	int i;
	
	for (i = 0; i < (strlen(s) / 2); i++) 
	{
		char temp1 = s[i];
		char temp2 = s[l-1];
		
		s[i] = temp2;
		s[l-1] = temp1;
		l--;
	}
}

int main() 
{
	char s[] = "Hallo Welt, ich bin's!";
	
	printf("%s\n", s);
	invert(s);
	printf("%s\n", s);
	invert(s);
	reverse(s);
	printf("%s\n", s);
	
	return 0;
}