21-day learning-through C++_DAY6

0. Pointers & Arrays

An array is a pointer to its first element, which is a pointer to an array variable. The (*) can be used for arrays, or ([]) for pointers, eg:

int mynums[5] = {0};

int* pnums = mynums;

You can use * (mynums+1), or you can use pnums[1].

1. Points to note when using the pointer

① Be sure to initialize the pointer variable to NULL;

② to verify that the pointer is valid before use ( check if null);

③new and delete to match, otherwise it will cause memory leaks ;

2, check whether the allocation request issued by new is satisfied

Method one: Using exception handling, catch (Bad_alloc)

1#include"stdafx.h"2#include <iostream>3 using namespacestd;4 5 intMain ()6 {7     Try8     {9         int* PAge =New int[536870911];Ten         Delete[] pAge; One     } A     Catch(bad_alloc) -     { -cout<<"error!"<<Endl; the     } -  -     return 0; -}

Law II: New (Nothrow)

1#include"stdafx.h"2#include <iostream>3 using namespacestd;4 5 intMain ()6 {7     8     int* PAge = New(nothrow) int[536870911];9     if(PAge)Ten     { One         Delete[] pAge; A     } -     Else -cout<<"error!"<<Endl; the  -     return 0; -}

3. Reference = = Alias

Reference, you can access the memory unit of the corresponding variable .

21-day learning-through C++_DAY6