动态内存

#define __STDC_WANT_LIB_EXTl__ 1
#include <stdio.h>
#include <stdlib.h>
typedef enum {false=0,true=1}bool;
/*
#define bool int
#define true 1
#define false 0
和上述一致均是为了声明bool的头文件，代替了stdbool.h
*/

int main(void)
{
    unsigned long long *pPrimes =NULL;
    unsigned long long trial =0;
    bool found =false;
    int total=0;
    int count=0;
    int i;

    printf("How many........");
    scanf_s("%d",&total); //比scanf安全

    total=total<4?4:total;

    pPrimes=(unsigned long long*)malloc(total*sizeof(unsigned long long));
    if (!pPrimes)
    {
        printf("not enough...
");
        return 1;
    }

    *pPrimes=2ULL;
    *(pPrimes +1)=3ULL;
    *(pPrimes+2)=5ULL;
    count =3;
    trial =5LL;

    while (count<total)
    {
        trial+=2ULL;

        for(i=1;i<count;i++)
        {
            if(!(found=(trial%*(pPrimes + i))))
                break;


        }
        if(found)
            *(pPrimes+count++)=trial;


    }


    for (i=1;i<total;i++)
        
            printf("%12llu",*(pPrimes + i));//%llu对应的数据类型为unsigned long long，这是C语言用来表示整数的最大类型
            if(!(i+1)%5)
                printf("
");
        }

    printf("
");

    free(pPrimes);
        pPrimes=NULL;

        system("pause");
        return 0;

}