使用 ifstream 读取.txt 并使用 ofstream 写入 new.txt 文件，但只有第一行有效

Question

I am trying to read a textfile, text.txt with text representing hexadecimal values:

0123456789abcdef 
0123456789abcdef
0123456789abcdef
0123456789abcdef
0123456789abcdef
0123456789abcdef
0123456789abcdef 

I am supposed to read this file and use ofstream to write to a new file output.txt to write the binary equiavalent of these hexademical values, with - representing 0's and # representing 1's.

Example:

0 = ----
1 = ---#
2 = --#-
...
F = ####

And my output for output.txt is

---#--#---##-#---#-#-##--####---#--##-#-#-####--##-####-####

when it should be

---#--#---##-#---#-#-##--####---#--##-#-#-####--##-####-####
---#--#---##-#---#-#-##--####---#--##-#-#-####--##-####-####
---#--#---##-#---#-#-##--####---#--##-#-#-####--##-####-####
---#--#---##-#---#-#-##--####---#--##-#-#-####--##-####-####
---#--#---##-#---#-#-##--####---#--##-#-#-####--##-####-####
---#--#---##-#---#-#-##--####---#--##-#-#-####--##-####-####
---#--#---##-#---#-#-##--####---#--##-#-#-####--##-####-####

My logic is there, but it seems that output.txt only writes the first line of text.txt . This makes me believe that I am only reading the first line.

I am forced to use c-style strings, hence the char array I am reading into.

Here is my code

#include <iostream>
#include <fstream>
using namespace std;

int main()
{
    ifstream myfile;
    myfile.open("test.txt");

    char words[10001] = {'\0'}; //c-style string
    if (myfile.is_open())
    {
        while (!myfile.eof())
        {
            myfile >> words; //read myfile text into char words[]

            ofstream outfile;
            outfile.open("output.txt"); //ofstream to output.txt based on character in words[]


            for (char c : words) //the ofstream to output.txt based on char c in words
            {
                if (c == '0')
                    outfile << "---#";
                else if (c == '2')
                    outfile << "--#-";
                else if (c == '3')
                    outfile << "--##";
                else if (c == '4')
                    outfile << "-#--";
                else if (c == '5')
                    outfile << "-#-#";
                else if (c == '6')
                    outfile << "-##-";
                else if (c == '7')
                    outfile << "-###";
                else if (c == '8')
                    outfile << "#---";
                else if (c == '9')
                    outfile << "#--#";
                else if (c == 'a')
                    outfile << "#-#-";
                else if (c == 'b')
                    outfile << "#-##";
                else if (c == 'c')
                    outfile << "##--";
                else if (c == 'd')
                    outfile << "##-#";
                else if (c == 'e')
                    outfile << "###-";
                else if (c == 'f')
                    outfile << "####";
            }
        }
        myfile.close();
    }

    return 0;
}

I suspect it's the myfile >> words , but I am not entirely sure. I added a few comments to try and explain the route I went.

Answer 1

You used

            ofstream outfile;
            outfile.open("output.txt");

inside the loop. This makes the file opened in each iteration and this will clear the contents of file. You should move this befoer the while loop.

Also note that your condition while (.myfile.eof()) is wrong . Instead of this, you should move the reading myfile >> words to the condition to check if reading is successful before using what is "read".

Answer 2

I would suggest this approach for the file handling:

ifstream infile("infile.txt");
ofstream outfile("outfile.txt");

if(infile.is_open()){
    while(!infile.eof()){
        //do the readings
    }
}else
{
    cout << "ERROR::FILE NOT SUCCESFULLY OPENED";
}