注意：strlen()與sizeof()的區別
不同型別的機器，測試結果可能有所不同

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


int main()
{
//  char *p=NULL;
    int  *p=NULL;
    int a[100];
    char b[1000];
    int i;
    int m = -20;
    unsigned n = 10;

    for(i=0;i<1000;i++)
    {
        b[i]=-1-i;
    }


    printf("m+n= %d \n"
 
,m+n);

    printf("strlen(b) = %d\n",strlen(b));

    printf("p= %d \n",sizeof(p));
    printf("*p= %d \n",sizeof(*p));
        printf("a= %d \n",sizeof(a));
    printf("a[100]= %d \n",sizeof(a[100]));
    printf("&a= %d \n",sizeof(&a));
    printf("&a[0]= %d \n",sizeof(&a[0]));

    return
 
 0;

}