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例1:在異常處理中處理析構(gòu)函數(shù)。
程序:
#include<iostream>
#include<string>
using namespace std;
class Student
{
public:
Student(int n, string nam)//定義構(gòu)造函數(shù)
{
cout << "constructor-" << n << endl;
num = n;
name = nam;
}
~Student()//定義析構(gòu)函數(shù)
{
cout << "destructor-" << num << endl;
}
void get_data();
private:
int num;
string name;
};
void Student::get_data()
{
if (num == 0)//如果num=0,拋出int型變量num
{
throw num;
}
else//如果num不等于0,輸出num,name
{
cout << num << " " << name << endl;
}
cout << "in get_data()" << endl;
}
void fun()
{
Student stud1(1101, "tan");
stud1.get_data();
Student stud2(0, "li");
stud2.get_data();
}
int main()
{
cout << "main begin" << endl;//表示主函數(shù)開始了
cout << "call fun()" << endl;//調(diào)用fun()函數(shù)
try
{
fun();
}
catch (int n)
{
cout << "num=" << n << ",error!" << endl;//num=0出錯
}
cout << "main end" << endl;//表示主函數(shù)結(jié)束
system("pause");
return 0;
}
程序分析:
main begin
call fun()
constructor-1101
1101 tan
in get_data()
constructor-0
destructor-0
destructor-1101
num=0,error!
main end
請按任意鍵繼續(xù). . .
例2:在上題的基礎(chǔ)上進行變形,分析執(zhí)行過程,由于異常處理調(diào)用了哪些析構(gòu)函數(shù)。
程序:
#include<iostream>
#include<string>
using namespace std;
class Student
{
public:
Student(int n, string nam)//定義構(gòu)造函數(shù)
{
cout << "constructor-" << n << endl;
num = n;
name = nam;
}
~Student()//定義析構(gòu)函數(shù)
{
cout << "destructor-" << num << endl;
}
void get_data();
private:
int num;
string name;
};
void Student::get_data()
{
if (num == 0)//如果num=0,拋出int型變量num
{
throw num;
}
else//如果num不等于0,輸出num,name
{
cout << num << " " << name << endl;
}
cout << "in get_data()" << endl;
}
void fun()
{
Student stud1(1101, "tan");
stud1.get_data();
try
{
Student stud2(0, "li");
stud2.get_data();
}
catch (int n)
{
cout << "num=" << n << ",error!" << endl;//num=0出錯
}
}
int main()
{
cout << "main begin" << endl;//表示主函數(shù)開始了
cout << "call fun()" << endl;//調(diào)用fun()函數(shù)
fun();
cout << "main end" << endl;//表示主函數(shù)結(jié)束
system("pause");
return 0;
}
程序分析:和上題的不同之處在與,本題在輸出“destructor-0”后,再執(zhí)行catch語句,輸出“num=0,error!”,fun函數(shù)執(zhí)行完畢,在流程轉(zhuǎn)回main函數(shù)之前先調(diào)用stud1的析構(gòu)函數(shù),輸出“destructor-1101”,最后執(zhí)行main函數(shù)中最后一行cout語句,輸出“main end”。
運行結(jié)果:
main begin
call fun()
constructor-1101
1101 tan
in get_data()
constructor-0
destructor-0
num=0,error!
destructor-1101
main end
請按任意鍵繼續(xù). . .
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