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Skip read lines in c ++ input file

So I am trying to read an input file into a two dimensional array.

The problem I'm running into is that I only want to read certain lines in my input file, but I just don't know where to put the second ignore in my code

Here is an input file named "Fruit.txt":

Oroblanco Grapefruit
Winter
Grapefruit

Gold Nugget Mandarin
Summer
Mandarin

BraeBurn Apple
Winter
Apple

And my code:

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

const int MAX_ROW = 6;
const int MAX_COL = 4;

void FileInput(string strAr[MAX_ROW][MAX_COL])
{

ifstream fin;

fin.open("Fruit.txt");

int columnIndex;
int rowIndex;

rowIndex = 0;

while(fin && rowIndex < MAX_ROW)
{
    columnIndex = 0;

    while(fin && columnIndex < MAX_COL)
    {
        getline(fin, strAr[rowIndex][columnIndex]);
        fin.ignore(10000,'\n');

        columnIndex++;

    }

    rowIndex++;
}


fin.close();
}

My code now saves it like this:

Oroblanco Grapefruit // strAr[0][0]
Grapefruit           // strAr[0][1] 

Gold Nugget Mandarin // strAr[0][2]
Mandarin             // strAr[0][3]

BraeBurn Apple       // strAr[1][0]
Apple                // strAr[1][1]

I want it to be like this:

Oroblanco Grapefruit // strAr[0][0]

Gold Nugget Mandarin // strAr[0][1]

BraeBurn Apple       // strAr[0][2]

I just don't know where I should place the second ignore. If I put this right after the first ignore then it will miss more than I want.

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2 answers


Your code is fine, just fix the variable columnIndex

.

and use 3 ignores because you need to ignore the empty line too.



fin.ignore(10000,'\n');
fin.ignore(10000,'\n');
fin.ignore(10000,'\n');
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There are several problems in your code:

  • colIndex

    - unused variable, possibly a problem with typos;
  • MAX_COL

    must be 3 not 4;
  • The order rowIndex

    is columnIndex

    wrong.

Instead



const int MAX_COL = 4;
while(fin && rowIndex < MAX_ROW)
{
    colIndex = 0;  // unused variable

    while(fin && columnIndex < MAX_COL)   // MAX_COL should be 3
    {
        getline(fin, strAr[rowIndex][columnIndex]);  // order problem
        fin.ignore(10000,'\n');

        columnIndex++;

    }

    rowIndex++;
}

use this:

const int MAX_COL = 3;  // MAX_COL should be 3
while(fin && rowIndex < MAX_ROW)
{

    columnIndex = 0;   // variable name fixed.
    while(fin && columnIndex < MAX_COL)
    {
        getline(fin, strAr[columnIndex][rowIndex]); // order matters
        if (strAr[columnIndex][rowIndex].empty() == false || 
            no_need_to_ignore()) {  // your sikp logic added here
            columnIndex++;
        }
    }
    rowIndex++;
}
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