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c++ifstream

c++ reading characters in from a file char by char using only char arrays[]


I am working on an assignment for my c++ class, and I am pretty close to solving my problem. At this point, I am getting output that is ALMOST what I was expecting, so I suspect that I may be misunderstanding a core concept of this problem. The part of my assignment I am working on now is to get a file name from the user, read in that file, and then display that file while replacing key characters. For example, :!, will be replaced with '\n' to make a new line. I am only allowed to use iostream and fstream, and all text must be handled with char arrays[]. In my current output, I am getting an extra space on the third line, and I do not understand how it is getting there. Because of this, I think I may have the logic wrong in my head, and was wondering if any more experienced programmers could explain where I am going wrong. Am I going in the right direction?

here is the text file I am using as practice: 1.txt

Type, type, type away :!
compile.
Run.
Hip hip hooray! :! No errors today! :!

This is the expected output of the same file: 1.txt

Type, type, type away
compile. Run. Hip hip hooray! 
No errors today!

this is the output that I am getting

Type, type, type away
compile. Run. Hip hip hooray! 
 No errors today! <<-------- extra space at the beginning!

I will paste my code below, feel free to critique it in any way.

#include <iostream>
#include <fstream>
using namespace std;
#define MAX 1024 // this is the maximum allowed number of char in a file.
                 // is it a bad idea to define it as a constant?

int main()
{
    char fileName[256];
    char data[MAX];
    int readFile(char fileName[],char data[]);
    void display(char data[], int counter);
    fstream file;

    cout << "File Name: ";
    cin >> fileName;

    int counter = readFile(fileName, data);
    display(data, counter);

    return 0;
}

int readFile(char fileName[], char data[])
{
    ifstream file;
    file.open(fileName);

    int count = 0;
    while(file.get(data[count]) && count < MAX)
    {
        count++;
    }
    file.close();
    return count;
}

void display(char data[], int counter)
{
    char formatText(char data[], int count);
    for(int i = 0; i < counter; i++)
    {
        if(data[i] == '\n') // I added this if statment in because the newline
        {                   // from the file was getting read, AND the :! was
            data[i] = '\0'; // becoming \n, printing out TWO new lines!
        }

    }
    for(int i = 0; i < counter; i++)
    {
        formatText(data, i);

        if(data[i] != ':') // All tokens have a : before, So i dont want to 
            cout << data[i]; // print out the :'s.
    }
}

char formatText(char data[], int count)
{
    if(data[count] == ':')
    {
        switch(data[count + 1]) // these are the three tokens I have been given,
        {                       // but it has to be expandable for more later.
            case '!': data[count + 1] = '\n';
                break;
            case '<': data[count + 1] = '\"';
                break;
            case '>': data[count + 1] = '\"';
                break;
        }
    }

}

I'm sorry if this has been answered in another post, I was unable to find (or possibly understand) the answer to my question. Thank you for your time and patience.


Solution

  • Type, type, type away :!
    compile.
    Run.
    Hip hip hooray! :! No errors. today! :!
    

    ok. the first thing you do in formatting is remove all the newlines '\n' in the character array and that leaves you with

    Type, type, type away :!compile.Run.Hip hip hooray! :! No errors today! :!
    

    then you replace all the !'s preceded by :'s with '\n' but if you notice that in this state all your :!'s have a non whitespace character in the next index position save one.

     :! No errors
    

    and that's your error, because it then replaces your sequence as \n No errors

    changing your input data to

    Type, type, type away :!
    compile.
    Run.
    Hip hip hooray! :!No errors today! :!
    

    fixes that extra space problem.