凯撒密码删除数据

我想知道是否有人会帮助我麻烦拍摄我的代码。它似乎正在正常工作，但是当我运行它的一半时，即使我从未打电话给任何内容来删除它。

所以例如，我的文件来自：

=======================
Rotated by 11 positions
=======================
Lnwypeyw lala sqz xa na lnwypeyw eb pdau sqz pwa w eppa
na pea bn znawec.
              -- F. L. IyAru**
to 
=======================
Rotated by 12 positions
=======================
Moxzqzx mbmb tra yb ob moxzqzx c qebv tra qxb x qqb
ob qb co aobxd.
              -- G. M. JzBsv

这是我的代码，我尝试过几次，这在逻辑上都很有意义，并且在丢失数据时不知道。

#include <iostream>
#include <cctype>
#include <fstream>
using namespace std;
bool isUpper(char character){
    //this will test and see if it's upper or lowercase
    bool upper;
    if(character>= 'A' && character <= 'Z'){
        upper=true;
    }
    else {
        upper= false;
    }
   return upper;
}
bool isLower(char character){
    //this will test and see if it's upper or lowercase
    bool lower;
    if(character >= 'a' && character <= 'z'){
        lower=true;
    }
    else {
        lower= false;
    }
   return lower;
}
//Actual function that will rotate the character
char rotate(char character, int offset) {
    char next_letter;
    //Changes it if it's a lower case
    if (isLower(character)) {
        next_letter = character + offset;
        if (next_letter > 'z'){
            next_letter = (next_letter - 26);
            return next_letter;
        }
        return next_letter;
    }
    else if(isUpper(character)) {
        next_letter = character + offset;
        if (next_letter > 'Z'){
            next_letter = (next_letter - 26);
            return next_letter;
        }
        return next_letter;
    }
    else {
       return character;
    }
}

int main() {
    //variables for program
    char character = 'a';
    int offset = 0;
    while(offset < 26){
        //opens the file  
        ifstream fin;
        fin.open("secretMessage.txt");
        if(!fin.good()) {
            cout << "Please check your file name!!!";
            return 0; 
        }
        //report for reading       
        cout << "=======================" << endl  
        << "Rotated by " << offset << " positions" << endl
        << "=======================" << endl; 
        //Reads until it's at the end of the file
        while ((! fin.eof())){
            character = fin.get();
            cout << rotate(character,offset);
        }
    //makes it run 26 times  
    ++offset;
    fin.close();
    cout << endl << endl;
    }
    //Closes the file output.
    return 0;
}