c++ - What are any side-effects of declaring something as size_t that I should be aware of? -

making class work stack (code not mine)

i have code this:

class stack { private:     int size;     int* data;     // next line mean?     size_t ptr;     public:   stack(int valid_stack_size) {     this->size = valid_stack_size;     this->ptr = 0;     this->data = new int[valid_stack_size]; }  void push(int value) {     if (this->ptr >= (size_t)this->size)         cout << "stack full" << endl;     this->data[this->ptr++] = value;  }  int pop() {     if (this->ptr == 0)         cout << "stack empty" << endl;      return this->data[--this->ptr];  }    }; 

what size_t ptr mean? size_t takes ptr value? or?

size_t type - defined in header file cstddef type can hold maximum size of object. on modern systems, it's equal size of pointer, , 64 bit (8 bytes). however, not required standard.

as result, line declares variable ptr of type size_t, confusing - ptr name suggest variable type should pointer.

on side note, code exhibits undefined behavior - when popping on empty stack or pushing full one.