Thread: Need help to display the process of partitioning and sorting of quick sorting

i still get errors: line 54 printIt undeclared, line 67 void printIt used prior to declaration, line 69 expected ';' before ')' token

Code:

#include <stdio.h>
#include <conio.h>  
 #define cutoff 3 
#define N 12 
 void swap(int *a,int *b)  
 {  
    int temp=*a;  
    *a=*b;  
    *b=temp;  
 }  
 int median(int a[],int left,int right)  
 {  
   int center=(left+right)/2;  
   if(a[left]>a[center])  
   swap(&a[left],&a[center]);  
   if(a[left]>a[right])  
   swap(&a[left],&a[right]);  
   if(a[right]<a[center])  
   swap(&a[right],&a[center]);  
   swap(&a[center],&a[right-1]);  
   return a[right-1]; 
 }  
 void insertionsort(int A[],int n)  
 {  
 int j,p,temp;  
 for(p=1;p<n;p++)  
 {  
 temp=A[p];  
 for(j=p;j>0&&A[j-1]>temp;j--)  
 A[j]=A[j-1];  
 A[j]=temp;
 }  
 }  
 void qsort(int a[],int left,int right)  
 {    
    int i,j,pivot;  
    if(left+cutoff<=right)  
    {  
     pivot=median(a,left,right);  
     i=left;  
     j=right-1;  
     while(1)  
     {  
         while(a[++i]<pivot){}  
         while(a[--j]>pivot){}  
         if(i<j)  
         swap(&a[i],&a[j]);  
         else  
         break;
         
     }  
     swap(&a[i],&a[right-1]);  
     qsort(a,left,i-1);
     printIt(a, left, i-1);    
     qsort(a,i+1,right);     
     printIt(a, i+1, right);     
    }  
    else  
    insertionsort(a+left,right-left+1); 
   
   
 }
 

 
 void printIt(int a[], int left, int right)
 {
   int i;
   for(i=left, i<right;i++)
      printf("%2d ",a[i]);
   printf("\n");
}
 
   
 void quicksort(int a[],int n)  
 {  
    qsort(a,0,n-1);  
 }   
 int main()  
 {  
   printf("Unsorted array:\n8,5,2,13,1,17,6,4,9,15,7,3\n");
   printf("Sorted array: \n");
   int a[]={8,5,2,13,1,17,6,4,9,15,7,3};  
   quicksort(a,12);  
   
   int i;  
   for(i=0;i<12;i++)  
   
    {
     printIt(a, 0, N);  
    }  
    getch();  
 }

Do you want to become an expert copy/paster or do you really want to learn programming?
You are already perfect in the former, but far away from the latter

Originally Posted by Low Chee Kwan

i still get errors: line 54 printIt undeclared, line 67 void printIt used prior to declaration,

You use printIt it on line 54, but declare and define it not until line 67 thus the compiler doesn't know in line 54 about it. The order is important and that's why you should use prototypes when you use many functions which call each other.

line 69 expected ';' before ')' token

Look carefully at each character of line 69 and you will find Adak's typo. If not I recommend spending some time learning C basics instead of desperately searching for someone who spoonfeeds you a solution for your homework.

Bye, Andreas

Thanks for noticing that, Andreas. Line 69 should have no commas in it, and have two semi-colons in it.


Since the original program didn't have prototypes for the functions, I'll share what we're talking about. These are the prototypes I'm using for my version of your program - They're very similar but perhaps not the exact same, as what you are using.

Code:

#include <stdio.h>

#define SIZE 10

/* These are the function prototypes */
void quickSort2(int a[], int n);
void printIt(int a[], int left, int right);
void swap(int a[], int left, int right);

int main(void) {
   int a[SIZE]={9,8,7,6,5,4,3,2,1,0};
   printIt(a, 0, SIZE);
   quickSort2(a, SIZE);

   //etc.
   return 0;
}

Note that the above is from my program, and you may need to change some particulars for yours, since I'm doing what I described for you, on a completely different Quicksort program, that is not compatible with yours. This is for general programming info ONLY, not specific code for your program. That should be an easy job, however.

Originally Posted by Adak

I'll answer you right after the Tour de France stage is over.

Unfortunately, I dozed off to sleep while the Tour was still riding the rather boring flat part of the stage, but this is the basics for using conio.h to write out colored text (foreground only).

Code:

/* 
I created an int *a1, above main() (outside any other function), to help with the printing display that I wanted. 
It works fine with the initial calls, but doesn't work well with the latter calls (yet), where the larger half of the 
array values get sorted. 

int *a1 = &a[0];

*/

void printIt(int a[], int left, int right, int pivot) {
   int i;

   for(i=0;i<SIZE && a[i] >-1;i++) {
      if(*(a1+i)==pivot) 
         _textcolor(14);  //14 is yellow
         
      else if(i<left || i>right) 
         _textcolor(2);   //2 is dull gray
      else
         _textcolor(10);
      _cprintf("%2d",*(a1+i)); //10 is bright green
   }
   putchar('\n');
   _textcolor(7);

}

If you are using Turbo C, you won't need the underline before these functions. My compiler requires them, because they are non-standard.

The console text (foreground) colors are:

0 = black
1 = blue
2 = green
3 = cyan
4 = red
5 = magenta
6 = brown
7 = white
8 = gray //these are repeated colors, but more intense
9 = bright blue
10 = bright green
11 = bright cyan
12 = bright red
13 = bright magenta
14 = yellow
15 = bright white

Note that you can do this and more, in console text colors, using a modern compiler, by including windows.h.