Question

I try to open a txt File for reading / writing in one task. My prior target is to exchange some characters by the saved ones in an array:

   void Inputfile::decryptFile(string filename)
{
    for(int i=0;i<15;i++)
    {
        fstream filedest(filename.c_str(), ios::in | ios::out);
        if(!filedest)
            cerr << "Konnte Zieldatei nicht oeffnen!
";
        else 
            cout << endl << filename << " geoeffnet zum entschluesseln!
";

        while(!filedest.eof())
        {
            filedest.get(ch);
            if(ch == char(this->mostcharsencrypted[i]))
            {
                filedest.put(char(this->mostchars[i]));
            }

        }
        filedest.close();
        cout << "Fertig!";
    }
}

mostcharsencrypted[] and mostchars[] are integer Arrays that hold the characters. I am sure that there is just 8 Bit Ansii Value in, and I check that even before this method gets called.

因此,如果目前读作的特性是目前阵列的位置(即:0至14)的特性,那么我就想与从主角的特征交换。

目前,我可以看到,我得到的正是配对类型,但我的笔记仍然显示同样的内容。

Answer 1

When replacing a file, usually two separate streams are used for input and output individually. If you need to use one stream for both input and output, the while loop will be like the following:

while(filedest)
{
    streampos p = filedest.tellg();
    if(!filedest.get(ch)) break;
    filedest.seekp(p);
    char ch2 = (ch == char(this->mostcharsencrypted[i])) ?
        char(this->mostchars[i]) : ch;
    filedest.put(ch2);
    filedest.sync();
}

友情链接