parameters in function

[zwpL3TCk]

Hi, I just wanna ask about the parameters in functions.
I'm currently studying the code i got from other site about quick sort algorithm.
There is some code i don't understand. Can someone explain me this codes?

void quicksort(int array[], int firstIndex, int lastIndex) // This is a function called quicksort.
                                   //The code inside the parameters is the declaration?
        pivotIndex = firstIndex; // This code and below codes can you explain how this codes work?
        index1 = firstIndex;
        index2 = lastInde


        while(index1 < index2) 
        {
            while(array[index1] <= array[pivotIndex] && index1 < lastIndex)
            {
                index1++;
            }
            while(array[index2]>array[pivotIndex])
            {
                index2--;
            }

[AbstractionAnon]

What is it you don't understand?

Line 1: This serves are the function definition and also the declaration, if it hasn't previously been declared.

The snippet you posted is not complete. index1, index2 and pivotIndex are not defined.

[zwpL3TCk]

I update the code i posted above.

[SamuelAdams]

Please post the entire program

[zwpL3TCk]

#include<stdio.h>

void quicksort(int array[], int firstIndex, int lastIndex)
{

    int pivotIndex, temp, index1, index2;

    if(firstIndex < lastIndex)
    {

        pivotIndex = firstIndex;
        index1 = firstIndex;
        index2 = lastIndex;


        while(index1 < index2)
        {
            while(array[index1] <= array[pivotIndex] && index1 < lastIndex)
            {
                index1++;
            }
            while(array[index2]>array[pivotIndex])
            {
                index2--;
            }

            if(index1<index2)
            {

                temp = array[index1];
                array[index1] = array[index2];
                array[index2] = temp;
            }
        }


        temp = array[pivotIndex];
        array[pivotIndex] = array[index2];
        array[index2] = temp;

        quicksort(array, firstIndex, index2-1);
        quicksort(array, index2+1, lastIndex);
    }
}

int main()
{
    //Declaring variables
    int array[100],n,i;

    printf("Enter the number of element you want to Sort : ");
    scanf("%d",&n);

    printf("Enter Elements in the list : ");
    for(i = 0; i < n; i++)
    {
        scanf("%d",&array[i]);
    }

    quicksort(array,0,n-1);

    printf("Sorted elements: ");
    for(i=0;i<n;i++)
    printf(" %d",array[i]);

    return 0;
}

From line 3 to line 42 and line 60.