字符串加密

#include<iostream>
using namespace std;
int main()
{
	int i, len,n;
	string s;
	cin >>n>> s;
	len = s.length();
	for (i = 0; i < len; i++)
	{
		if (s[i] >= 'A' && s[i] <= 'Z')
			s[i] += 'a' - 'A';
		else if(s[i] >= 'a' && s[i] <= 'z')
			s[i]-= 'a' - 'A';
	}
	for (i = 0; i < len; i++)
	{
		if (s[i] >= 'A' && s[i] <= 'Z')
		{
			s[i] += n;
			if(s[i] > 'Z')
			{
				s[i] -= 26;
			}
		}
		else if (s[i] >= 'a' && s[i] <= 'z')
		{
			s[i] += n;
			if (s[i] > 'z')
			{
				s[i] -= 26;
			}
		}
			
	}
	cout << s<<endl;
	return 0;

}