Question

I am trying to remove a column from a data set. My file looks as below. How can I accomplish this?

Input-

1,2,3,4
2,3,4,5
3,4,5,6

Output-

2,3
3,4
4,5

Answer 1

There is no quick way of doing that – you will end up “tokenizing” each line of the file, and then writing only the parts that you want.

If you know that each row contains a fixed number of integers (say, 4, as in your example), and you need to “cut out” several columns from it (say, columns 2 and 3), do this in a loop:

int a,b;
fscanf(inFile, "%*d,%d,%d,%*s", &a, &b);
fprintf(outFile, "%d,%d\n", a, b);

Of course you need to open the files before you start looping, close after you finish it, and test for the end of the input file in your loop condition.