ofstream Fehler

Question

Dies ist in Bezug auf eine andere Frage, die ich fragte, ob es seine eigene Frage ganz ist.

, wenn ich kompilieren bekomme ich zwei Fehler:

1> \ asst4.cpp (73):. Error C2065: 'outfile': undeclared Identifikator

1> \ asst4.cpp (73):. Fehler C2228: links von '.close' muss Klasse / Struktur / Union hat

Ich bin etwas verwirrt, was ich falsch gemacht habe hier? Irgendwelche reccomendations oder Ideen? (Die tatsächliche outfile ist in der Nähe der Spitze des Codes.

Hier ist der vollständige Code:

#include<iostream>
#include<fstream>  //used for reading/writing to files.
#include<string>    //needed for the filename.
#include<stdio.h>   //for goto statement

using namespace std;

int main()
{
    string start;
    char choice;
    char letter;
    int x;
    int y;
    int z;
    string filename;
    int garbage = rand()%('!' - '~' + 1 );
    cout << "Would you like to encrypt or decrypt a file? Please type enc, dec, or stop (case sensitive): " ;
    cin >> start;
    while(start == "enc")
    {
        x = 1;
        y = 1;
        cout << "How many garbage characters would you like between each correct character?: " ;
        cin >> z;
        cout << endl << "Please insert the name of the document you wish to encrypt, make sure you enter the name, and the file type (ie: filename.txt): " ;
        cin >> filename;
        ifstream infile(filename.c_str());
        while(!infile.eof())
        {
            ofstream outfile("encrypted.txt", ios::out);
            infile.get(letter); 
            if (x == y)         
                {
                outfile << garbage;
                x++;             
            }
            else
            {
                if((x - y) == z)            
                {
                    outfile << letter;          
                    y = x;                  
                }
                else                        
                {                           
                    outfile << garbage;
                    x++;
                }
            }
        }
        cout << endl << "Encryption complete...please return to directory of program, a new file named encrypted.txt will be there." << endl;
        infile.close();
        outfile.close();
        cout << "Do you wish to try again? Please press y then enter if yes (case sensitive).";
        cin >> choice;
        if(choice == 'y')
        {
            start = "enc";
        }
        else
        {
            cout << endl << "Do you wish to decrypt a file? Please press y then enter if yes (case sensitive).";
            if(choice = 'y')
            {
                start == "dec";
            }
            else
            {
                start == "no";
            }
        }
    }
    while(start == "dec")
    {

      //lets user choose whether to do another document or not.
      //used to track each character in the document.
        x = 1;    //first counter for tracking correct letter.
        y = 1;    //second counter (1 is used instead of 0 for ease of reading, 1 being the "first character").
              //third counter (used as a check to see if the first two counters are equal).
        //allows for user to input the filename they wish to use.
        cout << "Please make sure the document is in the same file as the program, thank you!" << endl << "Please input document name: " ;
        cin >> filename; //getline(cin, filename);  
        cout << endl;
        cout << "'Every nth character is good', what number is n?: ";
        cin >> z;   //user inputs the number at which the character is good. IE: every 5th character is good, they would input 5.
        cout << endl;
        z = z - 1;  //by subtracting 1, you now have the number of characters you will be skipping, the one after those is the letter you want.
        ifstream infile(filename.c_str()); //gets the filename provided, see below for incorrect input.
        if(infile.is_open()) //checks to see if the file is opened.
        {
            while(!infile.eof())    //continues looping until the end of the file.
            {   
                    infile.get(letter);  //gets the letters in the order that that they are in the file.
                    if (x == y)          //checks to see if the counters match...
                    {
                        x++;             //...if they do, adds 1 to the x counter.
                    }
                    else
                    {
                        if((x - y) == z)            //for every nth character that is good, x - y = nth - 1.
                        {
                            cout << letter;         //...if they don't, that means that character is one you want, so it prints that character.
                            y = x;                  //sets both counters equal to restart the process of counting.
                        }
                        else                        //only used when more than every other letter is garbage, continues adding 1 to the first
                        {                           //counter until the first and second counters are equal.
                            x++;
                        }
                    }
            }
            cout << endl << "Decryption complete...please return to directory of program, a new file named encrypted.txt will be there." << endl;
            infile.close();
            cout << "Do you wish to try again? Please press y then enter if yes (case sensitive).";
            cin >> choice;
            if(choice == 'y')
            {
                start == "dec";
            }
            else
                {
                cout << endl << "Do you wish to encrypt a file? Please press y then enter if yes (case sensitive).";
                if(choice == 'y')
                {
                    start == "enc";
                }
                else
                {
                    start == "no";
                }
            }
        }
        else  //this prints out and program is skipped in case an incorrect file name is used.
        {
            cout << "Unable to open file, please make sure the filename is correct and that you typed in the extension" << endl;
            cout << "IE:" << "     filename.txt" << endl;
            cout << "You input: " << filename << endl;
            cout << "Do you wish to try again? Please press y then enter if yes (case senstive)." ;
            cin >> choice;
            if(choice == 'y')
            {
                start == "dec";
            }
            else
            {
                start == "no";
            }
        }
        getchar();  //because I use visual C++ express.
    }
}

Dank der Zeit voraus! Jeff

Answer 1

Scoping Problem. Sie deklarieren outfile innerhalb Ihrer while-Schleife, noch versuchen sie außerhalb des für den Zugriff von While-Schleife.

Verschieben ofstream outfile("encrypted.txt", ios::out); auf die Zeile direkt nach dem ifstream infile(filename.c_str());, die vor Ihrem while(!infile.eof()) ist.

Answer 2

Sie haben zwei Möglichkeiten bekommen - als X-istence erwähnt, outfile.close der Grund, Ihr Anruf () nicht kompiliert ist, da das Objekt ‚outfile‘ nicht im gleichen Umfang wie die Deklaration von outfile existiert <. / p>

Sie können entweder die Linie verschieben

ofstream outfile("encrypted.txt", ios::out);

außerhalb der while-Schleife, so dass es die gleichen Regeln wie Scoping infile gehorcht, oder Sie können Ihren Anruf bewegen outfile.close (); innerhalb der While-Schleife, die sie in den aktuellen Bereich bewegen würden, in dem outfile vorhanden ist.

Meine Präferenz wäre die Erklärung der outfile außerhalb der while-Schleife zu bewegen, wie das Öffnen einer Datei ist eine ziemlich teure Operation und Sie wirklich nicht wollen, das Sie aus infile lesen für jeden Buchstaben tun. Öffnen Sie es einmal, schließen Sie es einmal ist der Weg, in diesem Fall zu gehen.