質問
これは私が尋ねた別の質問に関連していますが、完全に独自の質問です。
コンパイルすると、2つのエラーが発生します:
1>。\ asst4.cpp(73):エラーC2065: 'outfile':宣言されていない識別子
1>。\ asst4.cpp(73):エラーC2228: '.close'の左にはclass / struct / unionが必要です
ここで間違ったことをしたことについて、少し混乱していますか?お勧めやアイデアはありますか? (実際の出力ファイルはコードの上部にあります。
完全なコードは次のとおりです。
#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.
}
}
事前に感謝します! ジェフ
解決
スコープの問題。 whileループ内でoutfileを宣言していますが、前述のwhileループの外部でoutfileにアクセスしようとしています。
ofstream outfile(&quot; encrypted.txt&quot ;, ios :: out);
を ifstream infile(filename.c_str());
の直後の行に移動しますこれは、 while(!infile.eof())
の前にあります。
他のヒント
2つの選択肢があります-X-istenceが述べているように、outfile.close()への呼び出しがコンパイルされない理由は、オブジェクト 'outfile'がoutfileの宣言と同じスコープに存在しないためです。
行を移動することもできます
ofstream outfile("encrypted.txt", ios::out);
whileループの外側で、infileと同じスコープ規則に従うか、outfile.close()に呼び出しを移動できます。 whileループ内で、outfileが存在する現在のスコープに移動します。
ファイルを開くのは非常に高価な操作なので、outfileの宣言をwhileループの外側に移動することをお勧めします。実際には、infileから読み取るすべての文字に対してこれを行いたくありません。この場合は、一度開いてから閉じてください。