找出以下程序中的语法错误，并作出解释。
1 #include <stdlib.h> 2 int main() { 3 const int size; 4 size = 10; 5 int a[size]; 6 int *p1 = new int[size]; 7 int *p2 = malloc(sizeof(int)* size); 8 int *p3 = new int(size); 9 for(int i = 0; i < size; i++) { 10 a[i] = i; 11 p1[i] = a[i] * i; 12 p2[i] = p1[i] * i; 13 p3[i] = p2[i] * i; 14 } 15 int sum; 16 for(int i = 0; i < size; i++) 17 sum += a[i] + p1[i] + p2[i] + p3[i]; 18 cout << sum; 19 delete p1; 20 delete [] p2; 21 delete p3; 22 }
1 #include <iostream> 2 using namespace std; 3 class N { 4 static int n = 0; 5 int i; 6 public: 7 void N() : i(0) { } 8 void N(int a = 0) : i (a) { } 9 void N(int a = 0, int b) : i(a), n(b) { } 10 int get() const { return i++; } 11 void set(int a) { i = a;} 12 void print() const { cout << get() << endl;} 13 static int getn() const { return n; } 14 static void setn(int a) { n = a; i++; } 15 } 16 int main() { 17 cout << N::n << endl; 18 cout << N::getn() << endl; 19 cout << get() << endl; 20 cout << N::get() << endl; 21 cout << N::setn(10) << endl; 22 N *p = new N(5); 23 N n(); 24 n.set(10); 25 n.setn(11); 26 p.set(5); 27 delete p; 28 }
1 #include <string> 2 #include <iostream> 3 using namespace std; 4 class S { 5 public: 6 S(int a0) { cout << a0 << endl; } 7 S(double a0, int b0) : d(a0), b(b0){ cout << a0 << b0 << endl; } 8 S(char *p0) : d(a), b(2) { cout << p << endl;} 9 S(int &a0) : a(0), b(1), c("abc"), d(r), p(new int) { } 10 private: 11 int a; 12 const int b; 13 string c; 14 int &d; 15 int *p; 16 }; 17 int main() { 18 S a(1); 19 S b; 20 S c(0.0, 1); 21 S d("hello"); 22 S e(true); 23 S f(a); 24 e = a; 25 }
1 #include <string> 2 #include <iostream> 3 using namespace std; 4 class Person{ 5 public: 6 Person(string name) : name_ (name) { } 7 virtual void print() const = 0 { cout << name_; } 8 virtual bool compare(Person p) const { return p.name_ == name_; } 9 protected: 10 string name_; 11 }; 12 class Student : public Person { 13 Student(string name, string id) { name_ = name; id_ = id; } 14 Student(Person p, string id) { name_ = p.name_; id_ = id;} 15 bool compare(Student s) const { return s.name_==name_ && s.id_ == id_; } 16 void print() { cout << name_ << id_ << endl; } 17 private: 18 string id_; 19 }; 20 21 int main() { 22 Person p("Mike"); 23 Student s("jack", "12345"); 24 Student t(p, "23424"); 25 cout << s.compare(t); 26 cout << p.compare(t); 27 cout << s.compare(p); 28 s.print(); 29 s.Person::print(); 30 }
1 class Integer{ 2 public: 3 Integer(int a = 0) : i(a) {} 4 Integer operator+(int a, int b) { return a + b;} 5 Integer operator-() { return -i; } 6 Integer operator+() { return i; } 7 Integer operator++() { return ++i; } 8 Integer operator++(int) { return i++; } 9 bool operator<>(int a) { return i != a; } 10 private: 11 int i; 12 }; 13 void operator>>(ostream &os, Integer i) { 14 os << i; 15 } 16 istream & operator<<(istream &is, Integer i) { 17 is >> i.i; 18 return is; 19 } 20 Integer operator-(Integer a, Integer b) { 21 return a.i - b.i; 22 } 23 int main() { 24 Integer i(-1); 25 Integer j; 26 cin >> j; 27 i = -i; 28 i = i - j; 29 i = i + 10; 30 cout << i; 31 }
读程序，写出程序运行的结果
1 #include <iostream> 2 #include <string> 3 using namespace std; 4 int f( string a ); 5 int f( int b , int c = 1); 6 int f( bool b); 7 int main() { 8 string s = ""; 9 cout << f(s) << endl; 10 cout << f('\060') << endl; 11 cout << f(1, 2) << endl; 12 cout << f(false) << endl; 13 cout << f(0) << endl; 14 } 15 int f( string a) { 16 return a.length(); 17 } 18 int f( int b, int c) { 19 return b * c + b + c + 1; 20 } 21 int f(bool b) { 22 return b?1:-1; 23 }
1 #include <iostream> 2 using namespace std; 3 class Z { 4 public: 5 Z(int i) : id(i) { cout << id << " created" << endl; } 6 ~Z() { cout << id << " destroyed" << endl; } 7 Z(Z &z) : id(z.id) { cout << id << " created a copy" << endl; } 8 private: 9 int id; 10 }; 11 Z z(0); 12 int main() { 13 cout << "main start" << endl; 14 Z z1(1); 15 Z z2(2); 16 Z *z3 = new Z(3); 17 Z z4(z1); 18 }
1 #include <iostream> 2 using namespace std; 3 class X { 4 public: 5 X(int a) : x(a) { cout << "create X:" << x << endl; } 6 ~X() { cout << "destroy X:"<< x << endl; } 7 private: 8 int x; 9 }; 10 class Y : public X{ 11 public: 12 Y() : x(1), X(2) { cout << "create Y" << endl; } 13 ~Y() { cout << "destroy Y" << endl; } 14 private: 15 X x; 16 }; 17 18 int main() { 19 X x(5); 20 Y y; 21 }
1 #include <iostream> 2 using namespace std; 3 class B{ 4 public: 5 virtual void f() { cout << "B::f() "; } 6 void g() { cout << "B::g() "; } 7 virtual void h() { f(); } 8 }; 9 class D : public B { 10 public: 11 void f() { cout << "D::f() "; } 12 void g() { cout << "D::g() "; } 13 }; 14 int main() { 15 B b; 16 b.f(); b.g(); b.h(); 17 cout << endl; 18 B *p = &b; 19 p->f(); p->g(); p->h(); 20 cout << endl; 21 B *p = new D; 22 p->f(); p->g(); p->h(); 23 cout << endl; 24 B &r = *p; 25 r.f(); r.g(); r.h(); 26 cout << endl; 27 delete p; 28 }
1 #include <iostream> 2 using namespace std; 3 class B{ 4 public: 5 B () { cout << "create B" << endl; } 6 virtual ~B() { cout << "destroy B" << endl; } 7 virtual void f() { cout << "B::f()" << endl; } 8 virtual void f(int a) { cout << "B::f(int)" << endl; } 9 }; 10 class D : public B { 11 public: 12 D() { cout << "create D" << endl; } 13 virtual ~D() { cout << "destroy D" << endl; } 14 virtual void f() { cout << "D::f()" << endl; } 15 virtual void f(bool a) { cout << "D::f(bool)" << endl; } 16 }; 17 int main() { 18 B *p = new B; 19 p->f(); 20 p->f(0); 21 delete p; 22 p = new D; 23 p->f(); 24 p->f(0); 25 delete p; 26 D *d = new D; 27 d->f(); 28 d->f(0); 29 delete d; 30 }
1 #include <iostream> 2 using namespace std; 3 class D { 4 public: 5 D() { cout << "D created" << endl; } 6 D(D&) { cout << "D created a copy" << endl; } 7 ~D() { cout << "D destroyed" << endl; } 8 D& operator=(D&) { cout << "D assigned" << endl; return *this; } 9 void operator++() { cout << "operator++" << endl; } 10 void operator++(int) { cout << "operator++ with int" << endl; } 11 }; 12 int main() { 13 D d1; 14 D d2(d1); 15 d1 = d2; 16 ++d1; 17 d2++; 18 }
程序填空题
编程题，按要求编写程序
13. 实现字符串类string，声明如下 class string { public: string(const char *str = ""); // 普通构造函数 string(const string &other); // 拷贝构造函数 ~string(); // 析构函数 string & operator = (const string &other); // 赋值函数 bool operator==(const string &s); bool operator!=(const string &s); bool operator<(const string &s); bool operator>(const string &s); bool operator<=(const string &s); bool operator>=(const string &s); string operator +(const string &s); //连接 string operator +=(const string &s); int length() const; bool empty() const; char* c_str() { return m_data; } private: char *m_data; // 用于保存字符串 }; ostream &operator<<(ostream &os, const string &s); istream &operator>>(istream &is, string &s);