malloc & free

动态分配内存

#include<stdio.h>

#include<stdlib.h>



int compare_integers(void const *a,void const *b)

{

    register int const *pa = a;

    register int const *pb = b;



    return *pa>*pb ? 1:*pa<*pb ? -1:0;

}



int main()

{

    int *array;

    int n_value;

    int i;

    printf("How many values are there?\n");



    if(scanf("%d",&n_value)!=1 || n_value<0)

    {

        printf("Illegal numbers of values.\n");

        exit(EXIT_FAILURE);

    }



    array = (int *)malloc(n_value*sizeof(int));

    if(NULL == array)

    {

        printf("Cant get memery for that many values.\n");

        exit(EXIT_FAILURE);

    }

    

    for(i = 0;i<n_value;i++)

    {

        printf("?");

        if(scanf("%d",array+i)!=1)

        {

            printf("Error reading value #%d.\n",i);

            exit(EXIT_FAILURE);

        }

    }

    qsort(array,n_value,sizeof(int),compare_integers);



    for(i = 0;i<n_value;i++)

    {

        printf("%d ",array[i]);

    }



    free(array);

    return EXIT_SUCCESS;

}