C + + (c + + type enhancement)

C + + type enhanced type check more stringent

Assigns a pointer of a const type to a pointer of a non-const type. C language can pass through, but in C + + is not a part of the past

const  int  A = 10 ; a = 100 ; //const modified cannot modify the  int  *p = &a;*p = 100 ;p rintf ( "a =%d  \n  , a); //a = 100,c inside the type is not strict, the pointer can modify the const modified variable, is actually a is a const int * Type, that is, forcibly assigned to INT *, the const is omitted.  const  int  A with int const  A, Look at the const modifier who removed the type. int  *const  p; The int is removed, p cannot be changed, and the content of P points can be changed. const  int  *const  p; It points to itself and the content cannot be changed. 

#include<iostream>usingnamespace std;int main() {    constint100;//const修饰的必须要初始化    int *p = &a;//不可以报错 const int *无法转化成int *;    constint *p = &a;//才是正确的    //C++不需要强转    char *p = malloc(100);//C++会报错    char *q = (char*)malloc(100);//void *    return0;}

Boolean type (BOOL)

The logic of C language is represented by 0 and non-true. There are specific types in C + +.

int main(){    booltrue;    if(flag)        printf("hello world!\n");    else        printf("hello C++!\n");    return0;}

A true enumeration (enum)

The enumeration essence in C is an integral type, and an enumeration variable can be assigned with any integral type. In C + +, enumeration variables can only be initialized with the elements that are enumerated.

BOOL uses enumeration to implement the process:

#include<iostream>enum BOOL{    FALSE,TURE};int main(){    constint100;    BOOL flag = TRUE;    booltrue;    if(flag)        cout<<a;        printf("sizeof(flag) = %d sizeof(BOOL) = %d sizeof(bool) = %d\n",sizeof(flag),sizeof(BOOL),sizeof(bool));}//sizeof(flag) = 4 sizeof(BOOL) = 4 sizeof(bool) = 1//enum枚举本质是整型

It is not the actual data type but an object that will be learned by the string type.

enum SEASOM{    Spr,Sum,Autu,Win};int main(){    SEASON s;    s = Win;//在C++中比较严格，除了枚举外的无法赋值。c里面就可以赋其他值。    return0;}

In fact, enumerations can be equivalent to macros.

#define Spr 0#define Sun 1....enum{    1,Sum,Autu,Win};

In C + +, with the possible use of enumerations, Const replaces the use of macros.

The value of an expression can be assigned

C:

int main(){    int a,b=10;    100;//100赋值给b,b = 100这个表达式赋值给a。    100;//错误，表达式是不可被赋值的    1000;//错误    return0;}

C++

int main(){    int5;    100;    printf("a = %d b = %d\n",a,b);    1000;    printf("a = %d b = %d\n",a,b);    return0;}//a = 100,b = 5;//a = 1000,b = 5//a = b是一个表达式，b的值赋值给a,最后把100的值赋值给a,b的值没发生变化。

The limitation and promotion of C language embodied in C + +

CIN cout Class Object

scanf printf functions are functionally identical

int main(){    char name[30];    scanf("%s",name);//不安全的输入，输入很多会挂机    fgets(name,30,stdin);//最多只能输入29个字符，比较安全。    cin>>name;//>>流输入运算符    cout<<"name = "<<name<<endl;//"name = "字符串流入cout对象，name流入cout对象，endl(换行)流入cout对象中，从左至右的顺序。    string name1;    cin>>name1;    cout<<name1;    //很安全，输多少都不会挂机    cin>>a>>b;//有顺序，从键盘输入的第一个数流入a,第二个数流入b    //<=>    cin>>a;    cin>>b;    return0;}

C + + (c + + type enhancement)