c++ - issues in understanding pointers -

the following codes book programming interviews exposed having problem understand concept of pointers. why can't use code no. 1.

code no. 1

bool insertinfront( intelement *head, int data ) {     intelement *newelem = new intelement;     if( !newelem ) return false;     newelem->data = data;     head = newelem; // incorrect!     return true; } 

code no. 2

bool insertinfront( intelement **head, int data ) {     intelement *newelem = new intelement;     if( !newelem ) return false;     newelen->data = data;     *head = newelem; // correctly updates head     return true; } 

say calling function 1 as:

insertinfront(h, data); 

upon calling of function, computer makes duplication of arguments, release them when function returns. in code no.1, head=newelem assigned address of newelem head(which duplicate of h), released head, , address of newelem lost forever. in code no.2, however, function should called as:

insertinfront(&h, data); 

this means address of h duplicated head, , address of newelem assigned *head, i.e. head pointing, results in h. in way address of newelem after function returns.