// chapter6_6 with added strupper() function and %zd formats for strlen
//
/*------------------------------------------------------------*/
/*  Program chapter6_6                                        */
/*                                                            */
/*  This program illustrates the use of string functions.     */
#include <stdio.h>
#include <string.h>

#include <ctype.h>

void strupper( char s[]){
  // for( int i = 0; i < strlen(s); ++i) // worst, slowest, calls strlen every time through the loop
  // int n = strlen(s);
  // for( int i = 0; i < n; ++i) // better, call strlen once before the loop
  for( int i = 0; s[i] != 0; ++i) // best, fastest, no call to strlen, just stop at the zero byte
    s[i] = toupper(s[i]);
}

int main(void)
{
   /*  Declare and initialize variables.  */
   char strg1[]="Engineering Problem Solving: ";
   char strg2[]="Fundamental Concepts", strg3[50];
   /*  Print the length of strings.  */
   printf("String lengths: %zd %zd \n",
          strlen(strg1),strlen(strg2));
   /*  Combine two strings into one.  */
   strcpy(strg3,strg1);
   strcat(strg3,strg2);
   printf("strg3: %s \n",strg3);

   strupper(strg3); printf( "%s\n", strg3);

   printf("strg3 length: %zd \n",strlen(strg3));
   /*  Exit program.  */
   return 0;
}
/*---------------------------------------------------------*/

/* output:

String lengths: 29 20 
strg3: Engineering Problem Solving: Fundamental Concepts 
ENGINEERING PROBLEM SOLVING: FUNDAMENTAL CONCEPTS
strg3 length: 49 

*/