/*
Filename: encrypt_string.cs
Author : zhanghua
Date : 2005-08-11
Fuction : input a strig and encrypt a string


加密后的字符串的第一个字符是原先字符串的最后一个字符，其余的每一个字符是对应的原字符串中的前一个字符的值加上3。

example： welcome -> ezhofrp

*/
using System;

class Test
{
public static void Main()
{
string strInput, strOutput;

Console.WriteLine("please input a string to encrypt: \n");
strInput=Console.ReadLine();

Console.WriteLine(" your input string is : {0}\n", strInput);
//Encrypt(strInput);

strOutput = Encrypt(strInput);

Console.WriteLine("strOutput is :{0}\n", strOutput);
}

private static string Encrypt(string strInput)
{
string strFont, strEnd;
string strOutput;
char[] charFont;
int i,len, intFont;

len = strInput.Length;
//Console.WriteLine(" strInput 's length is :{0} \n", len);
strFont = strInput.Remove(len-1,1);
strEnd= strInput.Remove(0, len-1);

//Console.WriteLine(" strFont is : {0} \n" , strFont);
//Console.WriteLine(" strEnd is : {0} \n" , strEnd);

charFont = strFont.ToCharArray();
for(i=0; i<strFont.Length; i++)
{
intFont = (int)charFont[i] + 3;
//Console.WriteLine(" intFont is : {0} \n", intFont);

charFont[i]= Convert.ToChar(intFont);
//Console.WriteLine("charFont[{0}] is : {1}\n", i, charFont[i]);
}
strFont = ""; //let strFont null
for (i=0; i<charFont.Length; i++)
{
strFont += charFont[i];
}
strOutput=strEnd + strFont;
return strOutput;

}
}