艾默生软件工程师笔试题和面试题答案
1.考察虚继承内存体系
class A
{
public:
A() { cout<<"Construct A"<
~A() { cout<<"Destruct A"<
void speak() { cout<<"A is speaking!"<
};
class B:public virtual A
{
public:
B() { cout<<"Construct B"<
~B() { cout<<"Destruct B"<
};
class C:public virtual A
{
public:
C() { cout<<"Constuct C"<
~C() { cout<<"Destruct C"<
};
class D:public B, public C
{
public:
D(){ cout<<"Constsruct D"<
~D(){ cout<<"Destruct D"<
};
int main()
{
D *p = new D();
p->speak();
delete p;
}
输出：
Construct A
Construct B
Constuct C
Constsruct D
A is speaking!
Destruct D
Destruct C
Destruct B
Destruct A
2.考察非虚析构函数这道题
class Parent
{
public:
Parent(){cout<<"Parent construct"<
~Parent(){ cout<<"Parent destruct "<
};
class Child : public Parent
{
public:
Child() { cout<<"Child construct "<
~Child() {cout<<"child destruct"<
};
int main()
{
Parent *p;
Child *c = new Child();
p = c;
delete p; // 因为析构函数是非 virtual 的，故析构的时候按照指针的类型进行析构
}
输出：
Parent construct
Child Construct
Parent destruct
3.考察初始化列表的写法
class A
{
public:
A(int x, int y, int z):a=x,b=y,c=z {} (1)
A(int x, int y, int z):a(x),b(y),c(z){} (2)
private:
int a;
int b;
int c;
};
int main()
{
A a(1,2,3);
}
第 1 种写法是错误的，第 2 种正确。
4.考察拷贝构造函数和赋值的区别。
class A
{
public:
A() { cout<<"Construct A by default"<
A(const A& a) { cout<<"consttuct A by copy"<
A& operator =(const A& a) { cout<<"cosnt A by operator ="<
~A() { cout<<"Destruct A"<
};
int main()
{
A a;
A b=a; //调用拷贝构造函数
A c(a); //调用拷贝构造
A d;
d=a; //赋值
}
输出：
Construct A by default //构造对象 a
consttuct A by copy //拷贝构造 b
consttuct A by copy //拷贝构造 c
Construct A by default //构造 a
cosnt A by operator = //赋值 d=a
Destruct A
Destruct A
Destruct A
Destruct A
5.考察函数指针
voidfunc(char* a)
{
cout<
}
int main()
{
void (*fp)(char*); //填空处
fp = func; //函数名func相当于函数的地址，将其赋给函数指针fp
char* s="helloc";
fp(s);
}
