对象C++例

1 用类型说明的类型名，使用时不用冠以类型说明符 例1． typedef enum{red, green, yellow} traffic_light_color struct intersection { traffic_light_color traffic_light; int number_cars_queued; int cumulative_num_cars } intersection networks[50]; ------------------------------------------------------------------------ 枚举值转换为整型值是自动转换，而整型值转换为枚举值需要强制转换 例2 enum name {john, mike, rose, joan} name person1=john; name person2=1; name person2=(enum, name); ------------------------------------------------------------------------ 允许无名联合 例3. union { int i; float f; }; ------------------------------------------------------------------------ 增加了作用域运算符：： 例4. char ch; main() { hide_identifider(); printf(“\n\n global value of oh=%c”, ch); } void hide_identifier() { char ch=‟e‟ printf (“\n the local value of ch=%”, cj); … :: ch=‟a‟ } 输出结果为： the local value of ch=e the global value of ch=a 2

强制类型转换可采用函数形式 例5. long l=(long)f; 可写作： long l=long (f); ------------------------------------------------------------------------ 增加了类型说明new和delete 例6. void creat_string() { int num_char; printf (“how many character in your first_name :”; scanf (“%d, & num_chars); char *name=new char[num_chars+1]; printf (“enter your first name :”); scanf (“%s”, name); printf (“\n\n your first name, %s, is very nice!”, name); delete name; } ------------------------------------------------------------------------ main() { create_string(); … } ------------------------------------------------------------------------ 关于函数部分的给边和扩充 原形函数 例7. main() { int i=4, j=5; function (i, j); } void function (c, d) （原C语言的函数形式） int c, d; { printf (“\n c=%d, d=%d,” c, d) } void function (int c, int d) （C++语言的函数形式）

{ printf (“\n c=%d, d=%d,” c,d); } 3

缺省参数的函数 例8. void func (int a=0, char b=‟c‟, int d=10) { … } 下面的写法都允许 func (12) func(12, „w‟) func ( ) func (12, „kk‟, 30) ------------------------------------------------------------------------ 允许不限定参数个数的函数定义 例9. int print (char * …) ------------------------------------------------------------------------ 内联函数说明 例10. main() { int i=4, j=5; inline function (i, j); } void function (int a, int b) { … } ------------------------------------------------------------------------ 关于函数调用市的参数传递——引用类型 例11．（用C语言写交换两个字符的函数） void swap (v1, v2) int *v1, *v2; { int temp; temp = *v; *v1 = *v2, *v2 = temp; } main() { int i=7, j=8; swap (&i, &j); … } 4

（用C++语言写交换两个字符的函数） void swap (int& v1, int& v2) { int temp; temp = v1; v1 = v2; v2 =temp } main() { int i=7, j=8; swap (i, j); …. } ------------------------------------------------------------------------ 关于函数名重载 例12．（使用C语言的情况） int cube (int number) float fcube (float number) double dcube (double number) （使用C++语言的情况） int cube (int number) float cube (float number) double cube (double number) 5

类、对象和消息 class { [private: ] [protected: ] [public: ] }[对象表]； ------------------------------------------------------------------------ 例1．（类的说明） class point { private: int x; int y; public: int getx(){return x;} } ------------------------------------------------------------------------ class point { int x, y; public: int getx(); }; int point :: getx(){return x;} ------------------------------------------------------------------------ 例2.（对象的定义） point origin; point row[80]; point *point_ptr;

vector multiply (vector & v1, vector & v2) { … } ------------------------------------------------------------------------ 例3．（向对象发消息） origin . getx(); point_ptr → getx(); 6

构造函数和析构函数 例4. class point{ int x, y; public: int getx() {return x;} point (int a, int b); point (char a, char b); } point :: point (int a, int b) { x=a; y=b; } point :: point (char a, char b) { x= int (a); y= int (b); } ------------------------------------------------------------------------ 例5．（一个整数栈类的说明） class stack { private: int *top; int *bottom; public: stack() {top=bottom=new int [100];} void push (int c){if ((top_bottom)<100)*top++=c;} int pop() {if (--top>=bottom) return *top; } ~ stack () {delete bottom;} }; ------------------------------------------------------------------------ 使用整数栈类的例子——字母顺序反向 main() { char your_string[20]; printf (“\n enter your string:”); scanf (“%s”, your_string); printf (“\n your string is reversed %s”, reverse_str(your_string))； } ------------------------------------------------------------------------ char *reverse_str(char *string); { stack s; char *re_ptr; for (int i=0; ire_ptr=new char[strlen(string+1)];