C语言面试题 - 指针概念

C/C++知识点

题目：在 32bit 编译器下，写出运行结果：

char str[] = "Hello";
char *p = str;
int n = 10;
sizeof(str) = ( );
sizeof(p) = ( );
sizeof(n) = ( );
void func(char str[100]{
    sizeof(str) = ( );
}

答案：

char str[] = "Hello";
char *p = str;
int n = 10;
sizeof(str) = ( 6 ); //双引号自带一个
sizeof(p) = ( 4 );	 //32位系统char*为4位
sizeof(n) = ( 4 );	 //32位系统int为4位
void func(char str[100]{
    //c语言传入参数中如果为数组，并不会直接传入这么大的数组，而是转化为指针即char *str
    sizeof(str) = ( 4 );	
}

题目：已知代码如下，填空：

unsigned char *p1;
unsigned long *p2;
p1 = (unsigned char *)0x801000;
p2 = (unsigned long *)0x810000;
p1 + 5 = _______;
p2 + 5 = _______;

答案：

unsigned char *p1;
unsigned long *p2;
p1 = (unsigned char *)0x801000;
p2 = (unsigned long *)0x810000;
p1 + 5 = 0x801005;	//1个字节1个字节访问，1×5=5
p2 + 5 = 0x810014;	//4个字节4个字节访问，4×5=20，但是这里要转换成十六进制