C ++读取文件传输到2d数组

Question

So as the title says I'm trying to read from a file and save the characters into a 2d array with spaces but it gets stuck in the do while loop and last char of the file. any suggestions on how to fix this? i thought about using the eofbit but I couldn't figure it out then i tried exiting the do while loop by || it with eof that didnt work. it seems to just hang on the last letter of the file. thank you in advance for your advice

char ch[100][100];
int row_count =0;
int col_count = 0;
int col[100];
char temp; 
bool exit = false;
ifstream infile("data.txt");
if( infile.is_open())
{
    while(!infile.eof())
    {
        do
        {
            infile.get(temp);
            char[row_count][col_count] = temp;
            col_count++;

        }while(temp != '\n' || !infile.eof());
        col[row_count] = col_count;
        row_count++;
        col_count= 0;
    }
}

for(int i = 0; i <= 2; i++)
{
    for(int j=0; i <= col[i]; j++)
    {
        cout << ch[i][j];
    }
    cout << endl;
}

return 0;

}

Answer 1

The loop is because of the temp != '\\n' , at the end of the file this condition is always true, so the second condition is never verified because you check it with a or. If you want to keep your code, bring the !infile.eof() at the first place.

But if you want a best way and an easy way to read a file. You should use getline .

std::string line;
while(std::getline (infile,line))
{
    //do something for every char in the string...
}

Answer 2

I didn't compile this but this should work: Read the comments and learn from it.

#include <iostream> // for cout
#include <fstream> // for infile     

int main()
{
    const int RowSize = 100, ColSize = 100;
    char ch[RowSize][ColSize];
    int row_count = 0;
    int col_count = 0;
    int col[ColSize];
    char temp;
    bool exit = false;

    std::ifstream infile;

    infile.open("data.txt"); // open the file

    if (!infile.is_open()) // check if opened succseffuly
    {
        std::cout << "File didn't load successfully!" << std::endl; // prompt the user
        getchar(); // wait for any input
        return 0; // terminate
    }

    while (infile.get(temp)) // while reading succesffuly
    {
        // if you are here, means you have valid data

        if (temp == '\n') // check if end of the line
        {
            col_count = 0; // reset cols
            row_count++; // increment rows
            ch[RowSize][ColSize] = NULL; // lock char array
            continue; // continue the loop iteration
        }
        else
        {
            ch[row_count][col_count] = temp; // store temp in your array
        }
        col_count++; // increment cols on every read
    }

    for (int i = 0; i <= 2; i++) // this will display junk if your line is less than 100 characters (check NULL if you don't want that)
    {
        for (int j = 0; i <= col[i]; j++)
        {
            std::cout << ch[i][j];
        }
        std::cout << std::endl;
    }

    return 0;
}

Answer 3

iostream::eof will only return true after reading the end of the stream. It does not indicate, that the next read will be the end of the stream. Ref this . So, the modified code would look like the following code snippet.

char ch[100][100];
int row_count =0;
int col_count = 0;
int col[100];
char temp; 
bool exit = false;
ifstream infile("data.txt");
if( infile.is_open())
{
    while(!(infile>>temp).eof())
    {

        ch[row_count][col_count] = temp;
        col_count++;

        if(temp == '\n'){
            col[row_count] = col_count;
            row_count++;
            col_count= 0;
        }
    }
}

for(int i = 0; i <= 2; i++)
{
    for(int j=0; i <= col[i]; j++)
    {
        cout << ch[i][j];
    }
    cout << endl;
}

return 0;

}