transposing matrix from file to file

This is a discussion on transposing matrix from file to file within the C Programming forums, part of the General Programming Boards category; This is what I have, but when I run it the file that is printed out has a single number. ...

  1. #1
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    transposing matrix from file to file

    This is what I have, but when I run it the file that is printed out has a single number. Can anyone detect anything out of place?

    Code:
    #include <stdio.h>
    #define max_row 20
    #define max_col 20
    
    int main(void)
    {
    
        int matrix[max_row][max_col];
        int i, j, nr, nc;
        
       
        FILE * input;
        FILE * output;
       
        input = fopen("data.in.txt", "r");
        output = fopen("data.out.txt", "w");
        
        if(!input)
    	{
    		printf("failed to open file");
    	}
    	
    	/* read input*/
    	
    	fscanf(input, "%d%d", &nr, &nc);
        for(i = 0; i < nr; i++)
    	{
    		for(j = 0; j < nc; j++)
    		{
    			fscanf(input, "%d", &matrix[i][j]);
    		}
    	}
    		
    	/* print transpose in file*/ 
    	
    	for(j = 0; j < nc; j++)
    	{
    		for(i = 0; i < nr; i++)
    		{
    			fprintf(output, "%d ", matrix[i][j]);
        	}
        return 0;
        }
       }
    Thanks so much for looking at it.

  2. #2
    ATH0 quzah's Avatar
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    Can anyone detect anything out of place?
    Well, since you didn't actually show us an example of the input...

    Code:
    if(!input)
    	{
    		printf("failed to open file");
    	}
    What's the point of even checking to see if the file opened correctly if all you do is continue on regardless?

    Now let's see what happens when we learn how to indent properly, shall we?
    Code:
    int main(void)
    {
        int matrix[max_row][max_col];
        int i, j, nr, nc;
        FILE * input;
        FILE * output;
       
        input = fopen("data.in.txt", "r");
        output = fopen("data.out.txt", "w");
        
        if(!input)
        {
            printf("failed to open file");
        }
    	
        /* read input(even if we have no file to read from...)*/
    	
        fscanf(input, "%d%d", &nr, &nc);
        for(i = 0; i < nr; i++)
        {
            for(j = 0; j < nc; j++)
            {
                fscanf(input, "%d", &matrix[i][j]);
            }
        }
    		
        /* print transpose in file*/ 
        for(j = 0; j < nc; j++)
        {
            for(i = 0; i < nr; i++)
            {
                fprintf(output, "%d ", matrix[i][j]);
            }
            return 0;
        }
    }
    Much better.


    Quzah.
    Hope is the first step on the road to disappointment.

  3. #3
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    Sorry my indentation wasn't up to par. I'm not very good at this, obviously.

    As for an input, I must have forgotten
    it would look something like this:

    3 4
    1 2 3 5
    4 5 6 5
    7 8 9 5

    It only transposes the first column.

  4. #4
    ATH0 quzah's Avatar
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    Oct 2001
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    You seem to be missing the point. Your braces is in the wrong place, which is why I colored them for you. What exactly do you think that return statement inside your loop is going to do?


    Quzah.
    Hope is the first step on the road to disappointment.

  5. #5
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    Jul 2005
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    Thanks. I did realize that my braces weren't right. I fixed it, but the program still doesn't do what I'd like it to do. (thanks btw, I probably wouldn't have noticed it.)

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