/*
Reads an input file and prints the contents in all caps.  The program terminates when it reads a period.
A copy of the output is also stored in a string.  Input that contains no periods results in an infinite
loop ending in a segmentation fault.
*/

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>

int main( void ) {

   // Prompt user input.
   printf( "Enter some characters.\n" );

   // A char for storage.
   char c;


   // The program will run with a char array of predefined size because memory is allocated implicitly.
   // The program fails to execute using the char * because memory must be allocated explicitly when 
   // using a pointer to represent and populate a string, unless a string literal is used.
   // To see the program run correctly, comment line 30 and uncomment line 27.
   // To see the program cause a segmentation fault, comment line 27 and uncomment line 30.

   // A char array to store the output, with no segmentation fault as long as the length of the input isn't too long.
   char str[ 30 ];

   // A string to store the output, with a segmentation fault.
   //char *str;

   // Keep track of the length.  This variable being declared after *str means that memory must be allocated
   // to the pointer if you want to build a string with it.  Memory is allocated sequentially, so a segmentation
   // fault will result if you don't allocate any memory at line 30 above.
   int len = 0;

   // A pointer to use to populate the string.
   char *cp = str;

   // Read the input 1 char at a time.
   while( 1 ) {

      // The program quits when it sees a period.
      if ( ( c = getchar( ) ) == '.' ) {
         putchar( toupper( c ) );
         *cp = toupper( c );
         len++;
         break;
      }
      // Otherwise is echoes the char it read as upper case and reads the next one.  The upper case char is also stored in a string.
      else {
         putchar( toupper( c ) );
         *cp = toupper( c );
         cp++;
         len++;
      }
   }
   // A newline char at the end of the output.
   putchar( '\n' );

   return 0;
}