Reading vertically from a data

This is a discussion on Reading vertically from a data within the C Programming forums, part of the General Programming Boards category; Hi ppl. Beginner here.. I have a set of data 1 2 3 4 5 6 7 8 9 9 ...

  1. #1
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    Reading vertically from a data

    Hi ppl. Beginner here..

    I have a set of data

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

    how do i use a fscanf statement to read the third number in the second row(which is 7 as highlighted)? R is the variable I use to store the read value. And if I want to replace it with some other number, for example, get input from the user and replace the number 7 with 5, how do I do it? Below is my code. Thanks!

    Code:
    #include <stdio.h>
    #include <math.h>
    #include <stdlib.h>
    
    int main()
    {
    	FILE* fx= fopen("cool.txt","r");
    
    	int i,j,R;
    	
    	for(i=1;i<3;i++)
    	{		
    		for(j=1;j<4;j++)
    			fscanf(fx,"%d ",&R); 
    	}
    	fclose(fx);
    	printf("R is %d ", R);
    
    	return 0; 
    
    }

  2. #2
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    There's no need for a pair of nested loops when it can all be done using fscanf().
    Lookup the scanset feature of fscanf() and how to skip unwanted fields with "*".

  3. #3
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    my teacher want me to use the for loops.. haha Because we are just starting out on C programming. we haven't learnt skipping unwanted fields, he allows us only to use the stuff we learnt.. pls help!

  4. #4
    ATH0 quzah's Avatar
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    Well for starters, you can't replace anything, if you're opening in read mode. Anyway, you have to read the entire line before you can get to the second line. So you need to read a whole line, then start counting out as you read on the second line.


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

  5. #5
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    Code:
    int dummy;
    scanf("%d %d %d", &dummy, &dummy, &num);

  6. #6
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    Two loops, roughly:
    Code:
    one for loop for rows  {
       fscanf("%d %d %d", &skip, &skip, &skip);  //add %d and &skip for each column in a row
       one for column on the right row
       for(i = 1, 1 < 4; i++) {
          if(i == 3)
            fscanf("%d", &myNumber);
          else
            fscanf("%d", &skip);
      }
    }
    I wouldn't mess with fscanf()'s scanset features - they're a bit of a mess, to put it mildly.

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