C++参数传递

 1 #include<iostream>
 2 using namespace std;
 3 //值传递
 4 void sum(int a,int b)
 5 {
 6     a += 1;
 7     b += 1;
 8 }
 9 //引用传递
10 void sum2(int &a,int &b)
11 {
12     a += 1;
13     b += 1;
14 }
15 //指针传递
16 void sum3(int *a,int *b)
17 {
18     *a += 1;
19     *b += 1;
20 }
21 //默认参数
22 void sum4(int a = 4, int b = 5)
23 {
24     cout<<"a+b= "<<a+b<<endl;
25 }
26 int main()
27 {
28     int a = 1, b = 3;
29     cout<<"before sum:  a= "<<a<<"\tb= "<<b<<endl;
30     //值传递
31     sum(a,b);
32     cout<<"after sum:  a= "<<a<<"\tb= "<<b<<endl;
33     a = 1, b = 3;
34     cout<<"before sum2:  a= "<<a<<"\tb= "<<b<<endl;
35     //引用传递
36     sum2(a,b);
37     cout<<"after sum2:  a= "<<a<<"\tb= "<<b<<endl;
38     //指针传递
39     a = 1, b = 3;
40     sum3(&a,&b);
41     cout<<"after sum3:  a= "<<a<<"\tb= "<<b<<endl;
42     //默认参数
43     sum4();
44     cin.get();
45     return 0;
46 }