Difference

#include <stdio.h>

double difference(double array[], int size);

int main(void){
    double array[]={123.2,321.21,90.2, 3, 900};
    printf("The difference between the biggest and smallest elements is %f.\n",difference(array, 5));
    return 0;
}

double difference(double array[], int size){
    int i;
    float biggest=3;
    float smallest=-3;
    double *ptr;
    ptr=array;
    for(i=0; i<size; i++){
        if (*ptr>biggest){
            biggest=*ptr;
            ptr++;
        }

    }
    printf("The biggest number is %f.\n", biggest);

    for(i=0; i<size; i++){
        if ((*ptr<smallest)){
            smallest=*ptr;
            ptr++;
        }
    }
    printf("The smallest number is %f.\n", smallest);

    return (biggest-smallest);
}