操作C++ 标准库STL的动态数组，回顾python和perl的数组列表，感觉它们各有特色都非常精彩，花在它们上的学习时间很过瘾。我是在DeepIN系统上用gcc/g++，分享我用for和for_each操作C++的vector动态数组习练代码。

• 字符串数组的for
  这个for看上去非常像perl的列表数组 for (@msg)，如果把：看成了in它又像是python列表数组。C++中那个引用的&word就是msg数组中的元素，加上for它就遍历了所有的元素并用cout显示。

    vector<string> msg = {"Fine!", "the C++", "World", "from", "Deepin", "with ATOM!"};

    for (string &word : msg)
    {
        cout << word << " ";
    }
    cout << endl;

• 整数组成数组的for
  与字符串类似，操作方法不变。push_back是向数组未必追加元素。

    vector<int> v = {1,2,3,4};
    v.push_back(7); v.push_back(9);
    for (int &mint : v) {
        cout << mint << " " << endl;
    }

• 字符组成数组的for
  和整数、字符串操作类似。

    vector<char> v1 = {'a','b','c','d'};
    v1.push_back('m'); v1.push_back('n');
    for (char &mchar : v1) {
        cout << mchar << " " << endl;
    }

重点试练的字符串数组

    vector<string> v5 = {"aadf","sdfsf","werwr"};
    v5.push_back("hello"); v5.push_back("world");

    for (string &myvar : v5) {            //for (string myvar : v5)
      cout << myvar << " " << endl;
    }

这数组没什么特别的，for (string &myvar : v5) 也可以用 for (string myvar : v5)，也能正常编译，应该还是引用或叫别名效率更高吧。

还可以这样for操作，auto知道itemsi的类型。

    for (auto itemsi = v5.begin(); itemsi != v5.end(); itemsi++)
    {
      printf("v5b: ", *itemsi);
      cout << "v5b: " << *itemsi << endl;
    }

还可以给它加上迭代器指针，用指针操作。

    vector<string>::iterator iters;
    for (iters = v5.begin(); iters != v5.end(); iters++)
    {
      printf("v5a: ", *iters);
      cout << "v5a: " << *iters << endl;
    }

用for_each操作

    for_each(msg.begin(), msg.end(), funcs);
    for_each(v5.begin(), v5.end(), funcs);
    for_each(v.begin(), v.end(), funci);

funcs, funci分别是字符串和整数型函数，它们负责接收数组中的元素。比如：

void funcs(string elem)
{
    cout << elem << endl;
}
void funci(int elem)
{
    cout << elem*3 << endl;
}

下面是完整的习练代码

#include<functional>
#include<algorithm>
#include <iostream>
#include <vector>
#include <string>
#include <iterator>

using namespace std;

void funcs(string elem)
{
    cout << elem << endl;
}
void funci(int elem)
{
    cout << elem*3 << endl;
}

int main()
{
    vector<string> msg = {"Fine!", "the C++", "World", "from", "Deepin", "with ATOM!"};

    for (string &word : msg)
    {
        cout << word << " ";
    }
    cout << endl;

    vector<int> v = {1,2,3,4};
    v.push_back(7); v.push_back(9);
    for (int &mint : v) {
        cout << mint << " " << endl;
    }

    vector<char> v1 = {'a','b','c','d'};
    v1.push_back('m'); v1.push_back('n');
    for (char &mchar : v1) {
        cout << mchar << " " << endl;
    }

    vector<string> v5 = {"aadf","sdfsf","werwr"};
    v5.push_back("hello"); v5.push_back("world");

    for (string &myvar : v5) {            //for (string myvar : v5)
      cout << myvar << " " << endl;
    }

    for (auto itemsi = v5.begin(); itemsi != v5.end(); itemsi++)
    {
      printf("v5b: ", *itemsi);
      cout << "v5b: " << *itemsi << endl;
    }

    vector<string>::iterator iters;
    for (iters = v5.begin(); iters != v5.end(); iters++)
    {
      printf("v5a: ", *iters);
      cout << "v5a: " << *iters << endl;
    }

    for_each(msg.begin(), msg.end(), funcs);
    for_each(v5.begin(), v5.end(), funcs);
    for_each(v.begin(), v.end(), funci);

    return 0;
}

vector除了支持简单类型的数组外，也支持类作为元素，在for_each时把funcs或funci换成类中的函数，然后作为指针进行bind即可。我不知道C++依然这么优秀，很喜欢。继续学习，有高人路过请随时指导！