Using qsort to sort groups of numbers - C Function

C examples for Function:Utility Function

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Description

Using qsort to sort groups of numbers

Demo Code

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

#define NUM 40//  ww w. j  a va  2s .  c  om
void fillarray(double ar[], int n);
void showarray(const double ar[], int n);
int mycomp(const void * p1, const void * p2);

int main(void)
{
    double vals[NUM];
    fillarray(vals, NUM);

    showarray(vals, NUM);
    qsort(vals, NUM, sizeof(double), mycomp);

    showarray(vals, NUM);
    return 0;
}

void fillarray(double ar[], int n){
    int index;
    
    for( index = 0; index < n; index++)
        ar[index] = (double)rand()/((double) rand() + 0.1);
}

void showarray(const double ar[], int n){
    int index;
    
    for( index = 0; index < n; index++){
        printf("%9.4f ", ar[index]);
        if (index % 6 == 5)
            putchar('\n');
    }
    if (index % 6 != 0)
        putchar('\n');
}

/* sort by increasing value */
int mycomp(const void * p1, const void * p2){
    const double * a1 = (const double *) p1;
    const double * a2 = (const double *) p2;
    
    if (*a1 < *a2)
        return -1;
    else if (*a1 == *a2)
        return 0;
    else
        return 1;
}

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