C++索引越界的解决方法

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

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

#include #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templateclass vector : public std::vector {public:typedef unsigned size_type;

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

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

}

template vector(InputIterator first,InputIterator last): std::vector(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::size() ,"Index " << index << " must be less than " << std::vector::size());return std::vector::operator[](index);}

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

templateinline std::ostream& operator<< (std::ostream& os,const scpp::vector& v) {for(unsigned i=0 ;i

#endif

//test_vector.cpp#include "scpp_vector.h"#include

using namespace std;int main() {//usage-创建一个具有指定数量的vector：scpp::vector v(n); 把n个vector元素都初始化为一个值：scpp::vector v(n，val)//方法3：scpp::vector 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 vec;for(int i=0;i< 3;i++){vec.push_back(4*i);}cout << "The vector is : "<< vec <

#include "scpp_assert.h"

namespace scpp {

//wrapper around std::vector,在[]提供了临时的安全检查//fixed-size array templateclass 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

templateinline std::ostream& operator<< (std::ostream& os,const scpp::array& 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 #include //sort algorithm using namespace std;int main() {//use vector/array class instead of static array or dynamic array scpp::array 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;