c ++查找字符串

Program 1:

程序1：

#include <iostream>
using namespace std;
class Sample {
int X;
int* const PTR = &X;
public:
void set(int x);
void print();
};
void Sample::set(int x)
{
*PTR = x;
}
void Sample::print()
{
cout << *PTR - EOF << " ";
}
int main()
{
Sample S;
S.set(10);
S.print();
return 0;
}

Output:

输出：

11

Explanation:

说明：

In the above program, we created class Sample that contain member X and a constant pointer PTR that contains the address of X, here we cannot relocate the pointer but we can change the value of X using pointer PTR.

在上面的程序，我们创建的类样品含有成员X和包含X的地址，在这里我们不能搬迁的指针，但我们可以用指针PTR改变X的值恒定的指针PTR。

Here, we defined two member functions set() and print() outside the class.

在这里，我们在类外部定义了两个成员函数set()和print() 。

The set() function set the value to the data member X. and print() member function uses cout statement.

set()函数将值设置为数据成员X。 和print()成员函数使用cout语句。

cout << *PTR-EOF << " ";

The value of EOF is -1 then 10- -1 = 11.

EOF的值为-1，然后10- -1 = 11 。

Thus, 11 will be printed on the console screen.

因此，将在控制台屏幕上打印11 。

Program 2:

程式2：

#include <iostream>
using namespace std;
class Sample {
int X;
int* const PTR = &X;
public:
void set(int x);
void print();
};
void Sample::set(int x)
{
*PTR = x;
}
void Sample::print()
{
cout << *PTR - EOF << " ";
}
int main()
{
Sample* S;
S->set(10);
S->print();
return 0;
}

Output:

输出：

Segmentation fault (core dumped)
OR
Runtime error

Explanation:

说明：

The above code will generate a runtime error because in the above program we created the pointer of the class but, we did not initialize pointer PTR with any object of the Sample class. If we try to access the member of the class Sample then it will generate a runtime error.

上面的代码将产生运行时错误，因为在上面的程序中我们创建了该类的指针，但没有使用Sample类的任何对象初始化指针PTR 。 如果我们尝试访问Sample类的成员，则它将生成运行时错误 。

Program 3:

程式3：

#include <iostream>
using namespace std;
class Sample {
int X;
int* const PTR = &X;
public:
void set(int x);
void print();
};
void Sample::set(int x)
{
*PTR = x;
}
void Sample::print()
{
cout << *PTR - EOF << " ";
}
int main()
{
Sample* S = &(Sample());
S->set(10);
S->print();
return 0;
}

Output:

输出：

main.cpp: In function ‘int main()’:
main.cpp:25:27: error: taking address of temporary [-fpermissive]
Sample* S = &(Sample());
^

Explanation:

说明：

The above program will generate an error due to the below statement used in the main() function:

由于main()函数中使用了以下语句，因此上述程序将生成错误：

Sample *S = &(Sample());

Here we created a pointer of the class and tried to initialize with the object of the class, this is not the correct way. The correct way is,

这里我们创建了一个类的指针，并试图用该类的对象进行初始化，这不是正确的方法。 正确的方法是

Sample OB;
Sample *S = &OB;

翻译自: https://www.includehelp.com/cpp-tutorial/class-and-objects-find-output-programs-set-4.aspx

c ++查找字符串