This is my code

#include<bits/stdc  .h>
    using namespace std;
    int main()
    {
        char arr1[10][10];
        cout <<"Reading Start" <<endl;
        ifstream rfile("test.txt");
        rfile.getline(arr1[10],10);
        int i,j;
        for(i=0;i<6;i  )
        {
        for(j=0;i<6;j  )
        {
          cout << arr1[i][j];
        }
        }
        cout <<"\nRead Done" <<endl<<endl;
        rfile.close();
    }

This is my test.txt file

0 4 7 0 0 0
4 0 0 5 3 0
7 0 0 0 6 0
0 5 3 0 0 2
0 3 4 0 0 2
0 0 0 2 2 0

I want to read this matrix but when using the above code then it shows core dumped output, can anyone give me a better solution to do this thing?

CodePudding user response：

can anyone give me a better solution to do this thing?

A better alternative would be to use a 2D vector as shown below. The advantage of using a vector over an array is that you don't need to specify(know) the rows and columns beforehand. That is, the text input file can have as many rows and columns and there is no need to ask the user(or preallocate) how many rows and columns does the file have. std::vector will take care of it as shown below.

The below program uses a 2D std::vector for storing information(like integers values in this case) in 2D manner. After reading all the values from the file you can process the vector according to your needs. The program shown reads data(int values) from input.txt and store those in a 2D vector. Also, this program works even if there are uneven number of columns. You can use the below program as a reference(starting point).

#include <iostream>
#include <vector>
#include <string>
#include <sstream>
#include<fstream>
int main() {
    std::string line;
    int word;
    
    std::ifstream inFile("input.txt");
    
    //create/use a std::vector instead of builit in array 
    std::vector<std::vector<int>> vec;
    
    if(inFile)
    {
        while(getline(inFile, line, '\n'))        
        {
            //create a temporary vector that will contain all the columns
            std::vector<int> tempVec;
            
            std::istringstream ss(line);
            
            //read word by word(or int by int) 
            while(ss >> word)
            {
                //std::cout<<"word:"<<word<<std::endl;
                //add the word to the temporary vector 
                tempVec.push_back(word);
            }      
            //now all the words from the current line has been added to the temporary vector 
            vec.emplace_back(tempVec);
        }    
    }
    else 
    {
        std::cout<<"file cannot be opened"<<std::endl;
    }
    
    inFile.close();
    //now you can do the whatever processing you want on the vector

    //lets check out the elements of the 2D vector so the we can confirm if it contains all the right elements(rows and columns)
    for(std::vector<int> &newvec: vec)
    {
        for(const int &elem: newvec)
        {
            std::cout<<elem<<" ";
        }
        std::cout<<std::endl;
    }
    return 0;
}

The output of the above program can be seen