预测下列程序的输出
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
|
#include<iostream>
using namespace std;
class Test
{
protected:
int x;
public:
Test (int i):x(i) { }
void () const
{
cout << "fun() const called " << endl;
}
void ()
{
cout << "fun() called " << endl;
}
};
int main()
{
Test t1 (10);
const Test t2 (20);
t1.fun();
t2.fun();
return 0;
}
|
Output
1
2
|
fun() called
() const called
|
当函数返回指针或引用时，对const类型的函数进行重载将会十分有用。
如果参数带有const，会怎样
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
|
#include<iostream>
using namespace std;
void (const int i)
{
cout << "fun(const int) called ";
}
void (int i)
{
cout << "fun(int ) called " ;
}
int main()
{
const int i = 10;
fun(i);
return 0;
}
|
Output:
1
|
Compiler Error: redefinition of 'void fun(int)'
|
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
|
#include<iostream>
using namespace std;
void fun(char *a)
{
cout << "non-const fun() " << a;
}
void fun(const char *a)
{
cout << "const fun() " << a;
}
int main()
{
const char *ptr = "GeeksforGeeks";
fun(ptr);
return 0;
}
|
Output:
1
|
const fun() GeeksforGeeks
|
只有在const参数是指针或引用的情况下，函数重载才有效
近期评论