C++ 高级语法学习与总结（代码实例）

 1 //获取一个数据变量的类型
 2 #include<iostream>
 3 #include<stdlib.h>
 4 
 5 int main() {
 6 
 7     double db = 10.9;
 8     double *ps = &db;
 9     auto var =*ps;
10     std::cout<<typeid(var).name()<< std::endl;
11     getchar();
12   return 0;
13 }

 1 //关于宽字符的使用
 2 #include<iostream>
 3 
 4 #include<stdlib.h>
 5 #include<locale>
 6 
 7 int main(int argv ,char args []) {
 8 
 9     setlocale(LC_ALL, "chs");  //这就是设定为本地，中文简体
10     wchar_t * p2 = L"1234frd";
11     std::wcout << p2 << std::endl;
12     wchar_t *pi  = L"北京adas，你好！";
13     std::wcout << pi <<std::endl;
14 
15     getchar();
16     return 0;
17 }

 1 //新数组的使用
 2 #include<iostream>
 3 #include<array>
 4 #include<stdlib.h>
 5 
 6 
 7 int main(int argv ,char args []) {
 8 
 9    //array数据类型
10     
11     std::array<double ,5>data={2,3,4,5,6};
12     for (auto var : data) {
13         std::cout << "var =" << var << std::endl;
14     }
15     getchar();
16     return 0;
17 }

 1 //新数组的使用
 2 #include<iostream>
 3 #include<vector>
 4 #include<algorithm>
 5 #include<stdlib.h>
 6 
 7 int main(int argv ,char args []) {
 8 
 9     std::vector<int>  myvec;
10     myvec.push_back(1);
11     myvec.push_back(2);
12     myvec.push_back(3);
13     myvec.push_back(4);
14     myvec.push_back(5);
15     int res = 0;
16     //lambda 表达式  求和
17     //&res直接操作一个变量,res等价于返回值，x代表参数
18     //每次充当迭代器指向的元素，大括号就是代码
19     std::for_each(myvec.begin(), myvec.end(), [&res](int x) {res += x; });
20     std::cout << res << std::endl;
21     std::cin.get();
22   return 0;
23 }

/* 函数包装器管理内嵌函数 */
/*
  以一个简单的四则运算为例子
*/
//#pragma warning(disable: 2064)
#include<stdio.h>
#include<iostream>
#include<functional>

template <typename T ,typename F>
   T run(T a , T b , F f) {
    
       return f(a , b);
 }

int main(int argc , char * args []){

    using std::function;
    double db = 12.9; //double *
    //加 减 乘 除
    function<double(double,double)> Add = [](double a , double b) {
        return a+b;
    };
    function<double(double, double)> Sub = [](double a, double b) {
        return a - b;
    };
    function<double(double, double)> Mul = [](double a, double b) {
        return a*b;
    };
    function<double(double, double)>Div = [](double a, double b) {
        return a / b;
    };
    //定义一个函数数组
    function<double(double, double)>p[]= { Add,Sub,Mul,Div };
    char str[] = "+-*/";
    int i = 0;
    for(auto fun : p )
    std::cout <<"12 "<<str[i++]<<" 13 ="<< run<double>(12,13,fun) <<std::endl;
    std::cin.get();
  return 0;
}

 1 /* 函数包装器管理内嵌函数 */
 2 /*
 3   以一个简单的四则运算为例子
 4 */
 5 //#pragma warning(disable: 2064)
 6 #include<stdio.h>
 7 #include<iostream>
 8 #include<array>
 9 #include<functional>
10 
11 template <typename T ,typename F>
12    T run(T a , T b , F f) {
13     
14        return f(a , b);
15  }
16   double show(double  a, double  b) {
17 
18       std::cout << "这是一个外部函数，被调用" << std::endl;
19       return (a+b);
20   }
21 int main(int argc , char * args []){
22 
23     using std::function;
24     double db = 12.9; //double *
25     //加 减 乘 除
26     function<double(double,double)> Add = [](double a , double b) {
27         return a+b;
28     };
29     function<double(double, double)> Sub = [](double a, double b) {
30         return a - b;
31     };
32     function<double(double, double)> Mul = [](double a, double b) {
33         return a*b;
34     };
35     function<double(double, double)>Div = [](double a, double b) {
36         return a / b;
37     };
38     //定义一个函数数组
39     function<double(double, double)>p[]= { Add,Sub,Mul,Div ,show};
40     char str[] = "+-*/+";
41     int i = 0;
42     for(auto fun : p )
43     std::cout <<"12 "<<str[i++]<<" 13 ="<< run<double>(12,13,fun) <<std::endl;
44     std::cin.get();
45   return 0;
46 }