C - How to optimize code

Question

I have created this simple code: for size an array with 2 values (n and m) verify if n and m are >= 1. m = width and n = height. The code works but I'm sure it isn't optimized.

The code :

printf("Number of ligns.");
scanf("%d",n);
printf("Number of columns.");
scanf("%d",m);


if(*n >= 1)
{
    if(*m >= 1)
    {
        printf("Number of ligns : %x, Number of columns : %x \n", *n, *m);
    }
    else
    {
        while(*m < 1)
        {
            printf("Error, number of colums/ligns < 1. \n");
            scanf("%d",m);
        }
        printf("Number of ligns : %x, Number of columns : %x \n", *n, *m);
    }
}
else
{
    while(*n < 1)
    {
        printf("Error, number of colums/ligns < 1. \n");
        scanf("%d",n);
    }
            if(*m >= 1)
    {
        printf("Number of ligns : %x, Number of columns : %x \n", *n, *m);
    }
    else
    {
        while(*m < 1)
        {
            printf("Error, number of colums/ligns < 1. \n");
            scanf("%d",m);
        }
        printf("Number of ligns : %x, Number of columns : %x \n", *n, *m);
    }
}

Answer 1

You should provide a compiling code. I'll assume that n and m are int, but you should have added their declaration.

• You should use explicit names for variables. n is a line count, so call it line_count. m is column_count.
• You should check the return values of scanf to be sure you handle gracefully EOF and bad input.
• You print "Error, number of colums/ligns < 1. \n" every time, so the user can't know if it's the lines or the columns or both that are < 1.
• The english word is "lines", not "ligns".

• Your checks are too complicated and redundants. The entire if/else block can be replaced by this:

  while(*line_count < 1)
  {
      printf("Error, number of lines < 1. \n");
      scanf("%d", line_count);
  }
  
  
  while(*column_count < 1)
  {
      printf("Error, number of colums < 1. \n");
      scanf("%d", column_count);
  }
  
  printf("Number of lines : %x, Number of columns : %x \n", *line_count, *column_count);