sizeof(数组)

如何判断 int 普通数组a[]={0} ？

#include<stdio.h>
 
int main()
{
    int a[] = {1,2,3,4};
    printf("%d\n",sizeof(a)); //16
    printf("%d\n",sizeof(a+0));//4
    printf("%d\n",sizeof(*a)); //4
    printf("%d\n",sizeof(a+1)); //4
    printf("%d\n",sizeof(a[1])); //4
    printf("%d\n",sizeof(&a)); //4
    printf("%d\n",sizeof(&a+1));//4
    printf("%d\n",sizeof(&a[0]));//4
    printf("%d\n",sizeof(&a[0]+1)); //4
    getchar();
    return 0;
}

char arr[]={'a',...,'f'};

#include<stdio.h>
#include<string.h>
 
int main()
{
    char arr[] = {'a','b','c','d','e','f'}; 
    printf("%d\n", sizeof(arr)); //6
    printf("%d\n", sizeof(arr+0));//4
    printf("%d\n", sizeof(*arr));//1
    printf("%d\n", sizeof(arr[1]));//1
    printf("%d\n", sizeof(&arr)); //4
    printf("%d\n", sizeof(&arr+1));//4
    printf("%d\n", sizeof(&arr[0]+1));//4 
 
    printf("%d\n", strlen(arr));//随机值
    printf("%d\n", strlen(arr+0));//随机值
    //printf("%d\n",strlen(*arr));
    //printf("%d\n", strlen(arr[1]));
    printf("%d\n", strlen(&arr));//随机值
    printf("%d\n", strlen(&arr+1));//随机值
    printf("%d\n", strlen(&arr[0]+1)); //随机值
    getchar();
    return 0;
}

char *p="123456"

#include<stdio.h>
#include<string.h>
 
int main()
{
    char *p = "abcdef";
    printf("%d\n", sizeof(p));//4
    printf("%d\n", sizeof(p+1));//4
    printf("%d\n", sizeof(*p)); //1
    printf("%d\n", sizeof(p[0])); //1
    printf("%d\n", sizeof(&p)); //4
    printf("%d\n", sizeof(&p+1)); //4
    printf("%d\n", sizeof(&p[0]+1)); //4
 
    printf("%d\n", strlen(p)); //6
    printf("%d\n", strlen(p+1));//5
    //printf("%d\n", strlen(*p));
    //printf("%d\n", strlen(p[0]));
    printf("%d\n", strlen(&p));//随机值
    printf("%d\n", strlen(&p+1));//随机值
    printf("%d\n", strlen(&p[0]+1));//5 
    getchar();
    return 0;
}

char p[]="abc123"

#include<stdio.h>
#include<string.h>
 
int main()
{
    char p[] = "abcdef";
    
    printf("%d\n", strlen(p)); //6
    printf("%d\n", strlen(p+1));//5
    //printf("%d\n", strlen(*p));
    //printf("%d\n", strlen(p[0]));
    printf("%d\n", strlen(&p));//6
    printf("%d\n", strlen(&p+1));//随机值
    printf("%d\n", strlen(&p[0]+1));//5 
    getchar();
    return 0;
}

二维数组 int  a[3][4]={0}

#include<stdio.h>
#include<string.h>
 
int main()
{
    int a[3][4] = {0}; 
 
    printf("%d\n",sizeof(a)); //48
    printf("%d\n",sizeof(a[0][0]));//4;
    printf("%d\n",sizeof(a[0]));//16;
    printf("%d\n",sizeof(a[0]+1));//4
    printf("%d\n",sizeof(a+1)); //4
    printf("%d\n",sizeof(&a[0]+1));//4
    printf("%d\n",sizeof(*a)); //16
    printf("%d\n",sizeof(a[3])); //16
    getchar();
    return 0;
}

数组只有两种情况下表示整个数组：

• sizeof()中放的是数组名表示整个数组
• 取地址&数组名代表整个数组

其他都表示数组首地址或数组地址。