用c++编在程序中先声明int,float,char,double型的变量，再声明 int,rloat,char,double类型的指针变量，并用相应存储空间初始化指针变 量，分别显示这些指针变量占了多少字节，指针变量所指的变量占了多少宇 节。（提示用sizeof运算符）

以下是代码实现：
#include <iostream>
using namespace std;

int main() {
int a = 10;
float b = 3.14;
char c = 'A';
double d = 2.71828;

int* ptr1 = &amp;a;
float* ptr2 = &amp;b;
char* ptr3 = &amp;c;
double* ptr4 = &amp;d;

cout << "Size of int pointer: " << sizeof(ptr1) << endl;
cout << "Size of float pointer: " << sizeof(ptr2) << endl;
cout << "Size of char pointer: " << sizeof(ptr3) << endl;
cout << "Size of double pointer: " << sizeof(ptr4) << endl;

cout << "Size of int variable pointed by ptr1: " << sizeof(*ptr1) << endl;
cout << "Size of float variable pointed by ptr2: " << sizeof(*ptr2) << endl;
cout << "Size of char variable pointed by ptr3: " << sizeof(*ptr3) << endl;
cout << "Size of double variable pointed by ptr4: " << sizeof(*ptr4) << endl;

return 0;
}
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输出结果：
Size of int pointer: 8
Size of float pointer: 8
Size of char pointer: 8
Size of double pointer: 8
Size of int variable pointed by ptr1: 4
Size of float variable pointed by ptr2: 4
Size of char variable pointed by ptr3: 1
Size of double variable pointed by ptr4: 8
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解释：

sizeof 运算符返回变量或类型所占用的字节数。
int, float, char, double 分别占用 4 字节、4 字节、1 字节、8 字节。
指针变量占用 8 字节（因为我的机器是 64 位的）。
指针变量所指向的变量占用的字节数与变量类型相同。