c 迷惑1

1.
#include <iostream>
using namespace std;


void fun(int b[100])
{
cout << sizeof(b);//4

}


int main()
{
int *p = NULL;
sizeof(p); //4
sizeof(*p);//4
sizeof(int) *p; //error 4不能乘以指针

int a[100];
cout << sizeof(a) << endl;//400
cout << sizeof(a[100]) << endl;//4
cout << sizeof(&a) << endl;//4
cout << sizeof(&a[0]);//4

int b[100];

cout << sizeof(b) << endl;//400
fun(b);
}


2.
#include <iostream>
using namespace std;






int main()
{
int a[100];
cout << strlen(a) << endl;//不确定
int i;
for(i=0; i<1000; i++)
{
a[i] = -1-i; //vs2012出错，用int赋值char数组
}
cout << strlen(a) << endl;//255
return 0;
}
//strlen计算字符串长度，不包含字符串的“\0”
3.
#include <iostream>
using namespace std;


int main()
{
    int i = -20;
unsigned int j = 10;
cout << i+j; //4294967286
//无符号数和有符号数相加，都变成无符号数

    return 0;
}
4.
#include <iostream>
using namespace std;




int main()
{
    int* print;
cout << print << endl;//00000001
print++;
cout << print << endl;//00000005
print += 1;
cout << print << endl;//00000009


void* pvoid;
cout << pvoid << endl;//有地址
//pvoid++; //void* vs2012不能进行加法
(int*)pvoid++;//vs2012强转依然不能进行加法
cout << pvoid << endl;//强转int*,地址不会变
    return 0;
}




5.
#include<stdio.h>


int main()
{
const int s = 1;
    switch(1)
{
case(s): printf("yes");//vs2012出错，case表达式不是常量。如果是c++，可以正确执行
break;
default:
printf("default");
}
return 0;

}

6.


#include <stdio.h>


int main()
{
const volatile int i = 10; //没问题


//i = 12; //error 左值指定const对象
int f = i;
f = 88;


return 0;


}