/*
 * Write a function that takes a string
 * argument and capitalizes the letters in it.
 * Do this two ways:
 *   1. array subscripts
 *   2. pointer arithmetic
 * 
 */

#include <string.h>
#include <stdio.h>

// modify string[] in place
void to_upper_1(char string[]);

// same, but use pointers
void to_upper_2(char* string);

int main(){
  // The two possible string initialzations 
  // are *not* equivalent.
  // This is a character array, which is modifiable.
  char string1[] = "This is a 123 string.";
  // This is a string constant, which is not.
  //char* string2 = "So is 456 this.";
  char string2[] = "So is 456 this.";

  // This is the same sort of thing, too.
  int array[] = {10, 11, 12, 13, 14};
  // However, those notations work *only*
  // for initial declarations, not in the code.
  // So later 'string1="Hello"' is not legit.

  printf("string1 is '%s'\n", string1);
  printf(" calling to_upper_1(string1) \n");
  to_upper_1(string1);
  printf("string1 is '%s'\n", string1);  
  printf("\n");

  printf("string2 is '%s'\n", string2);
  printf(" calling to_upper_2(string2) \n");
  to_upper_2(string2);
  printf("string2 is '%s'\n", string2);  
  printf("\n");

  return 0;
}

void to_upper_1(char string[]){
  //printf(" ... in to_upper_1 ... \n");
  int i;
  for (i=0; i<strlen(string); i++){
    //printf(" '%c', ", string[i]);
    if (string[i] >= 'a' && string[i] <= 'z'){
      string[i] += ('A' - 'a');
    }
  }
  //printf("\n");
}

void to_upper_2(char* string){
  // This is Jim's version of 'the evil loop'
  while (*string){
    // printf(" at %p : '%c', \n", string, *string);
    if (*string >= 'a' && *string <= 'z'){
      *string += ('A' - 'a');
    }
    string++;
  }
}