(1) a，&a，和*a
int main(int argc, char *argv[]) {
int a = 10;
int *c = &a;
cout<<"a: "<<a<<"\t &a:"<<&a<<"\t c:"<<c<<"\t *c:"<<*c<<endl;
*c = 1;
cout<<"a: "<<a<<"\t &a:"<<&a<<"\t c:"<<c<<"\t *c:"<<*c<<endl;
a = 2;
cout<<"a: "<<a<<"\t &a:"<<&a<<"\t c:"<<c<<"\t *c:"<<*c<<endl;
return 0;
}
即：&是获取一个非指针的数据的地址，int a = 10中的a也是相当于一个“指针”指向0x22fd74，c也指向这个区域，一旦一方更改数据则将0x22fd74区域中的值更改了。
(2) 过程调用1
#include <iostream>
#include <string.h>
using namespace std;
/* run this program using the console pauser or add your own getch, system("pause") or input loop */
int add(int a, int b)
{
cout<<"into int add(int a, int b)"<<endl;
cout<<"a: "<<a<<"\t&a: "<<&a<<"\tb: "<<b<<"\tb: "<<&b<<endl;
int i = a;
a = b;
b = i;
cout<<"already,give control to main"<<endl;
cout<<"a: "<<a<<"\t&a: "<<&a<<"\tb: "<<b<<"\tb: "<<&b<<endl;
return a + b;
}
int main(int argc, char *argv[]) {
int a = 1, b = 2, c = 0;
int *ap = &a;
int *bp = &b;
cout<<"a: "<<a<<"\t&a: "<<&a<<"\tb:"<<b<<"\tb: "<<&b<<"\tc:"<<c<<"\t&c: "<<&c<<endl;
cout<<"ap: "<<ap<<"\t*ap: "<<*ap<<"\t&ap: "<<&ap<<endl;
cout<<"bp: "<<bp<<"\t*bp: "<<*bp<<"\t&bp: "<<&bp<<endl;
c = add(a, b);
cout<<"return to main:"<<endl;
cout<<"a: "<<a<<"\t&a: "<<&a<<"\tb: "<<b<<"\tb: "<<&b<<"c: "<<c<<"\t&c: "<<&c<<endl;
return 0;
}
即：在过程调用中的传参数的时候，形参是int型的，则只是传值，被调用过程不会影响调用过程中的参数，因为调用过程中的形参只是对实参的copy，形参和实参的地址是不同的。
（3）过程调用2
#include <iostream>
#include <string.h>
using namespace std;
/* run this program using the console pauser or add your own getch, system("pause") or input loop */
void add(int a, int b, int c)
{
cout<<"into void add(int a, int b, int c)"<<endl;
cout<<"a: "<<a<<"\t&a: "<<&a<<"\tb: "<<b<<"\tb: "<<&b<<"\tc: "<<c<<"\t&c: "<<&c<<endl;
int i = a;
a = b;
b = i;
c = a + b;
cout<<"already,give control to main"<<endl;
cout<<"a: "<<a<<"\t&a: "<<&a<<"\tb: "<<b<<"\tb: "<<&b<<"\tc: "<<c<<"\t&c: "<<&c<<endl;
}
int main(int argc, char *argv[]) {
int a = 1, b = 2, c = 0;
int *ap = &a;
int *bp = &b;
cout<<"a: "<<a<<"\t&a: "<<&a<<"\tb: "<<b<<"\tb: "<<&b<<"\tc: "<<c<<"\t&c: "<<&c<<endl;
// cout<<"ap: "<<ap<<"\t*ap: "<<*ap<<"\t&ap: "<<&ap<<endl;
// cout<<"bp: "<<bp<<"\t*bp: "<<*bp<<"\t&bp: "<<&bp<<endl;
add(a, b, c);
cout<<"return to main:"<<endl;
cout<<"a: "<<a<<"\t&a: "<<&a<<"\tb: "<<b<<"\tb: "<<&b<<"\tc: "<<c<<"\t&c: "<<&c<<endl;
return 0;
}
原理和2是一样的。
（4）过程调用3
#include <iostream>
#include <string.h>
using namespace std;
/* run this program using the console pauser or add your own getch, system("pause") or input loop */
int add(int *a, int *b)
{
cout<<"\ninto int add(int *a, int *b)"<<endl;
cout<<"a: "<<a<<"\t&a: "<<&a<<"\t*a: "<<*a<<endl;
cout<<"b: "<<b<<"\t&b: "<<&b<<"\t*b: "<<*b<<endl;
int i = *a;
*a = *b;
*b = i;
cout<<"already,give control to main"<<endl;
cout<<"a: "<<a<<"\t&a: "<<&a<<"\t*a: "<<*a<<endl;
cout<<"b: "<<b<<"\t&b: "<<&b<<"\t*b: "<<*b<<endl;
return *a + *b;
}
int main(int argc, char *argv[]) {
int a = 1, b = 2, c = 0;
int *ap = &a;
int *bp = &b;
cout<<"a: "<<a<<"\t&a: "<<&a<<"\tb: "<<b<<"\tb: "<<&b<<"\tc: "<<c<<"\t&c: "<<&c<<endl;
cout<<"ap: "<<ap<<"\t*ap: "<<*ap<<"\t&ap: "<<&ap<<endl;
cout<<"bp: "<<bp<<"\t*bp: "<<*bp<<"\t&bp: "<<&bp<<endl;
c = add(ap, bp);
//c = add(&a, &b);
cout<<"\nreturn to main:"<<endl;
cout<<"a: "<<a<<"\t&a: "<<&a<<"\tb: "<<b<<"\tb: "<<&b<<"\tc: "<<c<<"\t&c: "<<&c<<endl;
cout<<"ap: "<<ap<<"\t*ap: "<<*ap<<"\t&ap: "<<&ap<<endl;
cout<<"bp: "<<bp<<"\t*bp: "<<*bp<<"\t&bp: "<<&bp<<endl;
return 0;
}
可以看到在add中a，b和main中的ap，bp的地址不同，但是都是指向0x22fd7c和0x22fd78，所以在add中*a和*b的值交换了，即使得*（0x22fd7c）和*（0x22fd78）交换了，再返回到主函数中，由于a，ap，b，bp，分别指向0x22fd7c和0x22fd78，所以a，*ap，b，*bp的值也改变了。
在这里可以看到一个现象，在add中指针a的地址和指针b的地址和主函数中指针ap和指针bp的地址不一样，其实也是和之前（2），（3）一样，过程调用的时候形参只是复制实参的值，即将地址0x22fd7c和0x22fd78复制到了&a(0x22fc80)和&b(0x22fc88)中，是的*a即是*（0x22fd7c），*b即是*（0x22fd78）。
若是使用c = (&a, &b)，结果和上面一样。说明了实参ap传入的是ap的值，即和&a一样是0x22fd7c。
其结构如下：
（5）过程调用4
#include <iostream>
#include <string.h>
using namespace std;
/* run this program using the console pauser or add your own getch, system("pause") or input loop */
int add(int* &a, int* &b)
{
cout<<"\ninto int add(int *&a, int *&b)"<<endl;
cout<<"a: "<<a<<"\t&a: "<<&a<<"\t*a: "<<*a<<endl;
cout<<"b: "<<b<<"\t&b: "<<&b<<"\t*b: "<<*b<<endl;
int i = *a;
*a = *b;
*b = i;
cout<<"already,give control to main"<<endl;
cout<<"a: "<<a<<"\t&a: "<<&a<<"\t*a: "<<*a<<endl;
cout<<"b: "<<b<<"\t&b: "<<&b<<"\t*b: "<<*b<<endl;
return *a + *b;
}
int main(int argc, char *argv[]) {
int a = 1, b = 2, c = 0;
int *ap = &a;
int *bp = &b;
cout<<"a: "<<a<<"\t&a: "<<&a<<"\tb: "<<b<<"\tb: "<<&b<<"\tc: "<<c<<"\t&c: "<<&c<<endl;
cout<<"ap: "<<ap<<"\t*ap: "<<*ap<<"\t&ap: "<<&ap<<endl;
cout<<"bp: "<<bp<<"\t*bp: "<<*bp<<"\t&bp: "<<&bp<<endl;
c = add(ap, bp);
//c = add(&a, &b);
cout<<"\nreturn to main:"<<endl;
cout<<"a: "<<a<<"\t&a: "<<&a<<"\tb: "<<b<<"\tb: "<<&b<<"\tc: "<<c<<"\t&c: "<<&c<<endl;
cout<<"ap: "<<ap<<"\t*ap: "<<*ap<<"\t&ap: "<<&ap<<endl;
cout<<"bp: "<<bp<<"\t*bp: "<<*bp<<"\t&bp: "<<&bp<<endl;
return 0;
}
与上一种情况不一样，在这种情况中&a(add) = &ap(main)，&b(add) = &bp(main)。而这种情况的发生只是在add的形参前加了一个“&”。则在add过程中，a的定义就是int * &ap，即a是一个（int *）类型的引用，即是对ap的一个引用。（看某博客的解释）。
在深入理解计算机系统中，有“单操作数的操作符&和*可以产生指针和间接引用指针”，也就是，对于一个表示某个对象的表达式Expr，&Expr是给出该对象地址的一个指针，对于一个表示地址的表达式AExpr，*AExpr是给出该地址处的值，因此Expr和*&Expr是等价的。
还提到“指针用&运算符创建”和“运算符*用于指针的间接引用”，则&a(0x22fd68)是一个“指针”(指向0x22fd7c)，int *&a是对&a的一个“间接引用”或是一个“间接引用指针”（此时AExpr是0x22fd7c，*AExpr则是给出0x22fd7c的值）。
（6）过程调用5
#include <iostream>
#include <string.h>
using namespace std;
/* run this program using the console pauser or add your own getch, system("pause") or input loop */
void add(int* a, int* b, int *c)
{
cout<<"\ninto void add(int *a, int *b, int *c)"<<endl;
cout<<"a: "<<a<<"\t&a: "<<&a<<"\t*a: "<<*a<<endl;
cout<<"b: "<<b<<"\t&b: "<<&b<<"\t*b: "<<*b<<endl;
cout<<"c: "<<c<<"\t&c: "<<&c<<"\t*c: "<<*c<<endl;
int i = *a;
*a = *b;
*b = i;
*c = *a + *b;
cout<<"already,give control to main"<<endl;
cout<<"a: "<<a<<"\t&a: "<<&a<<"\t*a: "<<*a<<endl;
cout<<"b: "<<b<<"\t&b: "<<&b<<"\t*b: "<<*b<<endl;
cout<<"c: "<<c<<"\t&c: "<<&c<<"\t*c: "<<*c<<endl;
}
int main(int argc, char *argv[]) {
int a = 1, b = 2, c = 0;
int *ap = &a;
int *bp = &b;
int *cp = &c;
cout<<"a: "<<a<<"\t&a: "<<&a<<"\tb: "<<b<<"\tb: "<<&b<<"\tc: "<<c<<"\t&c: "<<&c<<endl;
cout<<"ap: "<<ap<<"\t*ap: "<<*ap<<"\t&ap: "<<&ap<<endl;
cout<<"bp: "<<bp<<"\t*bp: "<<*bp<<"\t&bp: "<<&bp<<endl;
cout<<"cp: "<<cp<<"\t*cp: "<<*cp<<"\t&cp: "<<&cp<<endl;
add(ap, bp, cp);
//add(&a, &b, &c);
cout<<"\nreturn to main:"<<endl;
cout<<"a: "<<a<<"\t&a: "<<&a<<"\tb: "<<b<<"\tb: "<<&b<<"\tc: "<<c<<"\t&c: "<<&c<<endl;
cout<<"ap: "<<ap<<"\t*ap: "<<*ap<<"\t&ap: "<<&ap<<endl;
cout<<"bp: "<<bp<<"\t*bp: "<<*bp<<"\t&bp: "<<&bp<<endl;
cout<<"cp: "<<cp<<"\t*cp: "<<*cp<<"\t&cp: "<<&cp<<endl;
return 0;
}
和之前的一样，&a(add) != &ap(main)，但是他们指向相同的地址，所以（add中的）改变能够有效。将add(ap, bp, cp)改成add(&a, &b, &c)结果一样。
（7）过程调用6
#include <iostream>
#include <string.h>
using namespace std;
/* run this program using the console pauser or add your own getch, system("pause") or input loop */
void add(int* &a, int* &b, int* &c)
{
cout<<"\ninto void add(int* &a, int* &b, int* &c)"<<endl;
cout<<"a: "<<a<<"\t&a: "<<&a<<"\t*a: "<<*a<<endl;
cout<<"b: "<<b<<"\t&b: "<<&b<<"\t*b: "<<*b<<endl;
cout<<"c: "<<c<<"\t&c: "<<&c<<"\t*c: "<<*c<<endl;
int i = *a;
*a = *b;
*b = i;
*c = *a + *b;
cout<<"already,give control to main"<<endl;
cout<<"a: "<<a<<"\t&a: "<<&a<<"\t*a: "<<*a<<endl;
cout<<"b: "<<b<<"\t&b: "<<&b<<"\t*b: "<<*b<<endl;
cout<<"c: "<<c<<"\t&c: "<<&c<<"\t*c: "<<*c<<endl;
}
int main(int argc, char *argv[]) {
int a = 1, b = 2, c = 0;
int *ap = &a;
int *bp = &b;
int *cp = &c;
cout<<"a: "<<a<<"\t&a: "<<&a<<"\tb: "<<b<<"\tb: "<<&b<<"\tc: "<<c<<"\t&c: "<<&c<<endl;
cout<<"ap: "<<ap<<"\t*ap: "<<*ap<<"\t&ap: "<<&ap<<endl;
cout<<"bp: "<<bp<<"\t*bp: "<<*bp<<"\t&bp: "<<&bp<<endl;
cout<<"cp: "<<cp<<"\t*cp: "<<*cp<<"\t&cp: "<<&cp<<endl;
add(ap, bp, cp);
//add(&a, &b, &c);
cout<<"\nreturn to main:"<<endl;
cout<<"a: "<<a<<"\t&a: "<<&a<<"\tb: "<<b<<"\tb: "<<&b<<"\tc: "<<c<<"\t&c: "<<&c<<endl;
cout<<"ap: "<<ap<<"\t*ap: "<<*ap<<"\t&ap: "<<&ap<<endl;
cout<<"bp: "<<bp<<"\t*bp: "<<*bp<<"\t&bp: "<<&bp<<endl;
cout<<"cp: "<<cp<<"\t*cp: "<<*cp<<"\t&cp: "<<&cp<<endl;
return 0;
}
对指针的引用。
说明此文章只是自己学习时候的产物，很可能有不对的地方或是奇怪的地方，_(:з」∠)_
若运气好有人要转载（内心os: 应该没有吧），米娜桑记得要申明下的说_(:з」∠)_
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