2009-03-07 51 views
0

這是參考我提出的另一個問題,儘管完全是它自己的問題。 ofstream error

我編譯時得到兩個錯誤:

1> \ asst4.cpp(73):錯誤C2065:OUTFILE':未聲明的標識符

1> \ asst4.cpp(73) :錯誤C2228:'.close'的左邊必須有class/struct/union

我有點困惑,因爲我在這裏做的不正確?任何建議或想法? (實際OUTFILE靠近代碼的頂部

下面是完整的代碼:!提前

                  
                    #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. 
    } 
} 

                  
                

感謝 傑夫

回答

2

範圍界定問題,你是你,而中聲明OUTFILE。環,但正試圖訪問它外面的說while循環。

移動 ofstream outfile("encrypted.txt", ios::out); 到行你 ifstream infile(filename.c_str()); 之後這是你的 while(!infile.eof()) 之前。

+0

做到了這一點,現在我的邏輯中存在一個實際的缺陷,某處它決定不打印到文件中......而就在我運行它之前,當我停止它,因爲它似乎已經凍結並打開txt文件,我實際上設法讓記事本崩潰,指向我! – Jeff 2009-03-07 11:17:45

0

你有兩個選擇 - 就像X-istence所提到的那樣,你調用outfile.close()的原因沒有被編譯,因爲對象'outfile'與outfile的聲明不在同一個範圍內。

你既可以招行

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

                        
                      

while循環外,使它服從相同的範圍規則爲INFILE,或者您可以將您的來電outfile.close();在while循環中,它將把它移動到outfile存在的當前作用域中。

我的偏好是將outfile的聲明移到while循環之外,因爲打開一個文件是一項相當昂貴的操作,而且您真的不想爲從infile讀取的每個字母執行此操作。打開它一次,關閉它一次是在這種情況下去的路。