这是我提出的另一个问题，尽管这完全是它自己的问题。
当我编译时，我得到两个错误：
1＆gt;。\ asst4.cpp（73）：错误C2065：'outfile'：未声明的标识符
1＆gt;。\ asst4.cpp（73）：错误C2228：'。close'的左边必须有class / struct / union
我对我在这里做错了什么感到有些困惑？任何推荐或想法？ （实际的outfile接近代码的顶部。
以下是完整代码：
#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.
}
}
提前致谢！ 杰夫
答案 0 :(得分：2)
范围问题。你在while循环中声明outfile，但是试图在所述while循环之外访问它。
将ofstream outfile("encrypted.txt", ios::out);移至您ifstream infile(filename.c_str());之前while(!infile.eof())之后的行。
答案 1 :(得分：0)
你有两个选择 - 正如X-istence所提到的，你调用outfile.close（）的原因是因为对象'outfile'与outfile的声明不在同一范围内。< / p>
你可以移动线
ofstream outfile("encrypted.txt", ios::out);
所以它遵循与infile相同的作用域规则，或者你可以将你的调用移动到outfile.close（）;在while循环中，它会将其移动到outfile存在的当前范围内。
我的偏好是将outfile的声明移到while循环之外，因为打开文件是一项非常昂贵的操作，而你真的不希望为从infile中读取的每个字母执行此操作。打开一次，关闭它一次就是这种情况。