const_iterator简单介绍

如果遇到常量容器类型，需要使用迭代器的时候，那么必须使用常量迭代器——const_iterator

#include <iostream>
#include <string>
#include <vector>
#include <deque>
#include <list>
#include <forward_list>
#include <string>
#include <array>
using namespace std;
#define LENGTH  10
typedef  int TYPE;
typedef  vector<TYPE> VECTORTYPE;
typedef  deque<TYPE> DEQUETYPE;
typedef  list<TYPE> LISTTYPE;
typedef  forward_list<TYPE> FORWARD_LISTTYPE;
typedef  array<TYPE,LENGTH>  ARRAYTYPE;
void print(VECTORTYPE & );
void print(DEQUETYPE & );
void print(LISTTYPE & );
void print(FORWARD_LISTTYPE & );
void print(ARRAYTYPE & );
void print(string &);
void print(list<string> &);
int main()
{
  list<string> names;
  vector<const char*> oldstyle = {"asdf","asdf"};
  //names = oldstyle;wrong ,type is not matching
  names.assign(oldstyle.begin(),oldstyle.end());
  print(names);

  const list<const char*> c_str{"const string1","const string2","const string3"};
//因为c_str是常量迭代器，它的迭代器必须是常量迭代器类型:const_iterator，例如下面会报错
 for(list<const char*>::iterator i = c_str.begin(); i != c_str.end(); ++i) 

    cout << *i << " ";
  
  return 0;
}
void print(VECTORTYPE &vec)
{
  for(VECTORTYPE::iterator i  = vec.begin() ; i != vec.end() ; ++i)
    { cout << *i << " ";}
  cout << endl;
  return ;
}

void print(DEQUETYPE &vec)
{
  for(DEQUETYPE::iterator i  = vec.begin() ; i != vec.end() ; ++i)
    { cout << *i << " ";}
  cout << endl;
  return ;
}

void print(LISTTYPE &vec)
{
  for(LISTTYPE::iterator i  = vec.begin() ; i != vec.end() ; ++i)
    { cout << *i << " ";}
  cout << endl;
  return ;
}

void print(FORWARD_LISTTYPE &vec)
{
  for(FORWARD_LISTTYPE::iterator i  = vec.begin() ; i != vec.end() ; ++i)
    { cout << *i << " ";}
  cout << endl;
  return ;
}

void print(ARRAYTYPE &vec)
{
  for(ARRAYTYPE::iterator i  = vec.begin() ; i != vec.end() ; ++i)
    { cout << *i << " ";}
  cout << endl;
  return ;
}

void print(string & s_vec)
{
  for(string::iterator i = s_vec.begin(); i != s_vec.end() ; ++i)  
    {cout << *i <<  " ";}
  cout << endl;
}
void print( list<string> &l)
{
  for(list<string>::iterator i = l.begin();i != l.end();++i)
    cout << *i << " ";
  cout << endl;

}

//上述代码会在g++编译器中报错：
r@r-Sys:~/c++/9/now$ ./123
asdf asdf 
const string1 const string2 const string3 r@r-Sys:~/c++/9/now$ g++ 11.cc -o 123
11.cc: In function ‘int main()’:
11.cc:33:50: error: conversion from ‘std::__cxx11::list<const char*>::const_iterator {aka std::_List_const_iterator<const char*>}’ to non-scalar type ‘std::__cxx11::list<const char*>::iterator {aka std::_List_iterator<const char*>}’ requested
   for(list<const char*>::iterator i = c_str.begin(); i != c_str.end(); ++i)

修改方法是：把代码中提示的那里的iterator改成：const_iterator即可