C++索引越界的解决方法

#define N 10
T static_arr[N]; //数组长度在编译时已知

int n=20;
T* dynamic_arr=new T[n]; //数组长度在运行时计算

std::vector<T> vector_arr; //数组长度在运行时进行修改

//scpp_vector.h
#ifndef  _SCPP_VECTOR_
#define  _SCPP_VECTOR_

#include <vector>
#include "scpp_assert.h"

namespace scpp {

    //wrapper around std::vector,在[]提供了临时的安全检查：重载[] <<运算符
    template<typename T>
    class vector : public std::vector<T> {
        public:
             typedef unsigned size_type;

             //常用的构造函数 commonly use cons
             explicit vector(size_type n=0) : std::vector<T>(n) {

             }
             vector(size_type n,const T& value) : std::vector<T>(n,value) {

             }

             template <class InputIterator> vector(InputIterator first,InputIterator last) 
                 : std::vector<T>(first,last) {

             }
             
             //Note : we don't provide a copy-cons and assignment operator  ?

            //使用scpp::vector提供更安全的下标访问实现，它可以捕捉越界访问错误
             T& operator[] (size_type index) {
                 SCPP_ASSERT( index < std::vector<T>::size() ,
                     "Index " << index << " must be less than " << std::vector<T>::size());
                 return std::vector<T>::operator[](index);
             }

             //? difference 
             const T& operator[] (size_type index) const {
                 SCPP_ASSERT( index < std::vector<T>::size() ,
                     "Index " << index << " must be less than " << std::vector<T>::size());
                 return std::vector<T>::operator[](index);
             }

             //允许此函数访问这个类的私有数据
             //friend std::ostream& operator<< (std::ostream& os,const ) ?
            };
} //namespace

template<typename T>
inline  std::ostream& operator<< (std::ostream& os,const scpp::vector<T>& v) {
    for(unsigned i=0 ;i<v.size();i++) {
            os << v[i];
            if( i+1 < v.size()) os << " ";
    }
    return os;
}


#endif

//test_vector.cpp
#include "scpp_vector.h"
#include <iostream>

using namespace std;
int main() {
    //usage-创建一个具有指定数量的vector：scpp::vector<int> v(n); 把n个vector元素都初始化为一个值：scpp::vector<int> v(n，val)
    //方法3：scpp::vector<int> v; v.reserve(n),表示开始的vector是空的，对应的size()为0,
    //并且开始添加元素时，在长度达到n之前，不会出现导致速度降低的容量增长现象
    scpp::vector<int> vec;
    for(int i=0;i< 3;i++){
        vec.push_back(4*i);
    }
    cout << "The vector is : "<< vec <<endl;

    for(int i=0;i <= vec.size();i++) {
        cout << "Value of vector at index " << i << " is " << vec[i] << endl;
    }
    return 0;
}

//scpp_array.h
#ifndef _SCPP_ARRAY_H_  
#define _SCPP_ARRAY_H_

#include "scpp_assert.h"

namespace scpp {

//wrapper around std::vector,在[]提供了临时的安全检查
//fixed-size array
template<typename T,unsigned int N>
class array {
    public:
         typedef unsigned int size_type;

         //常用的构造函数 commonly use cons
        array() {}
        explicit array(const T& val) {
            for(unsigned int i=0;i < N;i++) {
                     m_data[i]=val;
                 }
        }
                 
        size_type size() const { 
            return N;
        } //must use const if we use the size()
             
        //Note : we don't provide a copy-cons and assignment operator  ?

        T& operator[] (size_type index) {
             SCPP_ASSERT( index < N,
                     "Index " << index << " must be less than " << N);
             return m_data[index];
         }

         //? difference 
        const T& operator[] (size_type index) const {
             SCPP_ASSERT( index < N ,
                     "Index " << index << " must be less than " << N);
             return m_data[index];
        }

         //模拟迭代器的begin和end方法
         //访问方法accessors
        T* begin() { 
            return &m_data[0];
        }

        const T* begin() const { 
            return &m_data[0];
        }

         //返回越过数组尾部的迭代器
        T* end() { 
             return &m_data[N];
        }

        const T* end() const { 
             return &m_data[N];
        }
    private:
        T m_data[N];
    };
} //namespace scpp

template<typename T,unsigned int N>
inline  std::ostream& operator<< (std::ostream& os,const scpp::array<T,N>& v) {
    for(unsigned int i=0 ;i< N;i++) {
            os << v[i];
            if( i+1 < v.size()) os << " ";
    }
    return os;
}
#endif

//test_array.cpp
#include "scpp_array.h"
#include <iostream>
#include <algorithm> //sort algorithm
using namespace std;
int main() {
    //use vector/array class instead of static array or dynamic array
    scpp::array<int,5u > arr(0); 
    arr[0]=7;
    arr[1]=2;
    arr[2]=3;
    arr[3]=9;
    arr[4]=0;

    cout << "Array before sort : " << arr << endl;
    sort(arr.begin(),arr.end());
    cout << "Array after sort : "<< arr << endl;

    arr[5]=8;
    return 0;
}