C++ Memory 分配new[]和delete[]

Question

I'm trying to dynamically allocate a new object.

  int len = (nm == NULL) ? 0 : strlen(nm);

try {
  name = new char[len + 1];
}
catch(std::bad_alloc) {
  name = NULL;
}
if(name) {
    if(nm == NULL)
        strcpy(name, "");
    else
    {
        strcpy(name, nm);
        cmds=new command [num_of_cmds];

Then my destructor has them being deleted via

robot::~robot()
{
if (name) {
    delete[] name;
}
delete [] cmds;
} 

I keep getting segementation faults, if i edit some code to initialize a value on a simple int, it breaks. My delete[] cmds breaks so i have to comment it out. Any help would be greatly appreciated. I will clarify more things if people need.

Answer 1

When your robot' name is NULL ( nm == NULL ), you alloc an empty string, but don't alloc cmds . So you should at least set cmds to NULL in that branch, or check in destructor if (name && *name != 0) before delete [] cmds; . I'd go with the first option...

Answer 2

Unless you have a very good reason not to, you should avoid using new[] and delete[] and instead use std::string and std::vector . These handle memory management for you; and are considerable easier to use because of that.

std::vector is far more useful than a manually allocated buffer, not only because it handles memory for you, but it is still compatible with older C-style APIs. In situations where you need to provide a const char * or char * , you can simply provide &vec[0] (as in, the address of the first element of the std::vector ).

std::string makes memory management, string manipulation, and (in conjunction with std::stringstream ) string formatting much, much, much easier. Don't be tempted to deal with memory management yourself, use the well-tested std::string and std::vector .