Book: Absolute Beginners problem

[Slingshottheory]

I'm a complete beginner working through the "C Programming for Absolute beginners" book.
Every once in a while I run into an example that won't compile correctly. I'm trying to run an end of chapter program the book has written in it. And it compiles, and tries to run, then crashes.

Being so new to c programming I'm not entirely sure what to look for since the Dev-c++ compiler I use didn't pick up an error before running the program.

Below is the code, would much appreciate any thoughts or tips, anything I missed.

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

//define new data type
typedef struct deck{
        
        char type[10];
        char used;
        int value;
        }aDeck; //end type
        
  //func proto
  void shuffle( aDeck *);
  
main()
{//start main

   int x,y;
   
   aDeck myDeck[52];
   
   srand ( time(NULL) );
   
   //initialize struct array
   for (x=0; x<3; x++){//start for
     for(y=0; y<13; y++){//start for
     
     switch (x){//start switch
     
         case 0:
              strcpy(myDeck[y].type, "diamonds");
              myDeck[y].value=y;
              myDeck[y].used='n';
              break;
         
         case 1:
              strcpy(myDeck[y + 13].type, "clubs");
              myDeck[y+13].value=y;
              myDeck[y+13].used='n';
              break;
         
         case 2:
              strcpy(myDeck[y + 26].type, "hearts");
              myDeck[y+26].value=y;
              myDeck[y+26].used='n';
              break;
         
         case 3:
              strcpy(myDeck[y +39].type, "spades");
              myDeck[y+39].value=y;
              myDeck[y+39].used='n';
              break;
              
              }//end switch
              }//end inner for
              }//end outer for
         
         shuffle(myDeck);
        
        
   }//end main
   
   void shuffle(aDeck * thisDeck)
{//start func

   int x;
   int iRnd;
   int found=0;
   
   system("cls");
   printf("\nYour five cards are: \n\n");
   
   while (found <5){//start while
      
    iRand=rand() % 51;
      
      if (thisDeck[iRnd].used=='n'){//start if
          
          switch(thisDeck[iRnd].value){//start switch
             
             case 12:
                  printf("Ace of %s\n", thisDeck[iRnd].type);
                  break;
             
             case 11:
                  printf("King of %s\n", thisDeck[iRnd].type);
                  break;
             
             case 10:
                  printf("Queen of %s\n", thisDeck[iRnd].type);
                  break;
             
             case 9:
                  printf("Jack of %s\n", thisDeck[iRnd].type);
                  break;
             
             default:
                     printf("%d of ", thisDeck[iRnd].value+2);
                     printf("%s\n", thisDeck[iRnd].type);
                     break;
                     }//end switch
                     
             thisDeck[iRnd].used='y';
             found = found+1;
             }//end if
             }//end while
      }//end shuffle

[hk_mp5kpdw]

for (x=0; x<3; x++){//start for

1) That should probably be x < 4.

void shuffle(aDeck * thisDeck)
{//start func

   int x;
   int iRnd;
   int found=0;
   
   system("cls");
   printf("\nYour five cards are: \n\n");
   
   while (found <5){//start while
      
    iRand=rand() % 51;
      
      if (thisDeck[iRnd].used=='n'){//start if
          
          switch(thisDeck[iRnd].value){//start switch
             
             case 12:
                  printf("Ace of %s\n", thisDeck[iRnd].type);
                  break;
             
             case 11:
                  printf("King of %s\n", thisDeck[iRnd].type);
                  break;
             
             case 10:
                  printf("Queen of %s\n", thisDeck[iRnd].type);
                  break;
             
             case 9:
                  printf("Jack of %s\n", thisDeck[iRnd].type);
                  break;
             
             default:
                     printf("%d of ", thisDeck[iRnd].value+2);
                     printf("%s\n", thisDeck[iRnd].type);
                     break;
                     }//end switch
                     
             thisDeck[iRnd].used='y';
             found = found+1;
             }//end if
             }//end while
      }//end shuffle

2) Is the iRnd/iRand thing a typo? If not then this value (iRnd) isn't being set and has a completely random value (not the random range that you expect) and is likely causing the error when you try to access thisDeck[234576] (as an example) because you are attempting to access memory that you don't own.
3) rand() % 51 produces a range from 0 through 50 meaning index 51 never gets picked, you probably want rand() % 52 instead.

[CommonTater]

Ok ... a few things...
DEVC++ is terribly outdated (and thus not a very good learning tool) it's been abandoned for nearly a decade. You would do well to update. If you are doing plain C coding I suggest Pelles C or if you're also doing C++ you might try Code::Blocks with MinGw (google is your friend).

Tutorials and books often have mistakes in them... It's kind of a challenge to find them and fix them, shows you're learning...

I just ran your code through Pelles C and here are the errors I got...

Building main.obj.
E:\c_Code\Experiments\testconsole\main.c(17): warning #2099: Missing type specifier; assuming 'int'.
E:\c_Code\Experiments\testconsole\main.c(77): error #2048: Undeclared identifier 'iRand'.
E:\c_Code\Experiments\testconsole\main.c(68): warning #2114: Local 'x' is not referenced.
*** Error code: 1 ***
Done.

Note that the line numbers are in brackets, so you shouldn't have too much trouble finding them...
the first one is because it's not ... main() ... it's .... int main (void) and main always returns a value (usually 0).

When I fixed the errors it ran nicely.

[Slingshottheory]

Thank you both for analyzing my newbie code, very helpful!


I'm switching over to Pelles C, latest version, see what I can do with it.

Thanks again

[CommonTater]

Thank you both for analyzing my newbie code, very helpful!
I'm switching over to Pelles C, latest version, see what I can do with it.
Thanks again

Before you get too far into it... it's quite different than DEV... so spend some time in the help file. Pelles C has the best help system I've ever seen.
Especially be sure to read up on how to create projects... it's slightly non-obvious until you get the hang of it.