このコードは何をしますか？ （メモリ管理）

Question

char *p = new char[200]; 
char *p1 = p; 
char *p2 = &p[100]; 
delete [] p1; 

がところでこれは私が実際にこれを知っておく必要がありますテストか何かではありません:)

Answer 1

// allocate memory for 200 chars 
// p points to the begining of that 
// block 
char *p = new char[200]; 
// we don't know if allocation succeeded or not 
// no null-check or exception handling 

// **Update:** Mark. Or you use std::no_throw or set_new_handler. 
// what happens next is not guranteed 

// p1 now points to the same location as p 
char *p1 = p; 

// another pointer to char which points to the 
// 100th character of the array, note that 
// this can be treated as a pointer to an array 
// for the remaining 100-odd elements 
char *p2 = &p[100]; 

// free the memory for 200 chars 
delete [] p1; 

// **Update:** Doug. T 
// [...] p and p2 are now pointing to freed memory 
// and accessing it will be undefined behavior 
// depending on the executing environment.