squares.h

   1
   2 #include "basics.h"
   3 #include <math.h>
   4
   5 int is_even (int num)
   6 {
   7   return (num % 2);
   8 }
   9
  10 char* inside_out (char* string)
  11 {
  12   int length = strlen(string);
  13   int center = is_even(length);
  14   char* result = calloc(sizeof(char), length + 2); // for newline and
  15                                                    // NUL
  16   int half = (length / 2) - 1; // account for 0-index
  17
  18   for (int i = 0; i < length; i++)
  19     {
  20       if (i == half)
  21         result[i] = string[0];
  22
  23       else if (center && (i == (half + 1)))
  24         continue;
  25
  26       else if (i == (half + 1 + center))
  27         result[i] = string[length - 1];
  28
  29       else if (i <= half)
  30         result[i] = string[i + 1];
  31
  32       else
  33         result[i] = string[i - 1];
  34     }
  35
  36   result[length + 1] = '\n';
  37   return result;
  38 }
  39
  40
  41 char* generate_square(char* string)
  42 {
  43   int length = strlen(string);
  44   // The size is for the square, the newlines and the NUL-term
  45   int result_size = (length * length) + length;
  46   char* result = calloc(sizeof(char), result_size);
  47
  48   char* current = string;
  49   for (int i = 0; i < length; i++)
  50     {
  51       strcat(result, current);
  52       result[(length + 1) * (i + 1)] = '\n';
  53       current = inside_out(current);
  54     }
  55
  56   return result;
  57 }