New operator: It allows dynamic storage allocation. It throws an exception if memory allocation fails. The general format of new operator is return type, pointer to data type.
The C++ statement
Allocates memory to variable ptrvar dynamically of specified data type and specified size. The operator new allocates a specified amount of memory during run time and returns a pointer to that memory allocation. It compares the size of memory allocated by
Size of (data type) * integer type size;
Where data type can be a standard data type or a user defined data type, integer size can be an integer expression, which specifies the number of element in the array. The new operators returns the NULL, if memory allocation is unsuccessful
Example: Int * a = new (100);
It creates a memory for an integer and initializes it with 100.
Delete operator: This is used to return the memory allocated by new operator back to the memory pull. Memory thus released will be reused for other part of programme. Although memory allocated by is returned automatically to the system. When the programme terminates it is safer to use this operator explicitly within the pointer. This is absolutely necessary in situations where local variable pointing to the memory get destroyed when the function terminates leaving memory inaccessible to the rest of the delete operator is-
Deal locates the memory allocates to ptrvar. By de allocating the memory, the pointer variable does not get deleted and the address value stored in it does not change. However this address become invalid, as the returned memory will be used up for storing entirely different data.