malloc vs new in C++

In this chapter of C++ interview questions, we will learn about:

• malloc in c++ and malloc syntax
• new in c++ and new syntax
• malloc vs new in c++

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To provide flexibility to the programmers, Dynamic Memory Allocation(DMA) is an important concept.

 

It allocates memory in the Heap. Its application is wide like you can use for variable-length array as well for Data Structures like a linked list, tree.

 

C uses calloc() and malloc() for DMA.

C++ also has this along with new & delete operators for allocating and free memory.

 

Unused memory needs to be de-allocated otherwise there will be a Memory Leak issue

Lets learn a bit more about malloc and new in c++ along with their syntax.

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Malloc() in C++

malloc() in C++ is a library function used for allocating memory dynamically.

 

Malloc() in C++:

• allocates a block of memory, but doesn't initialize.
• and returns a pointer of void.

malloc syntax

ptr =(datatype*) malloc(size);

New in C++

New in C++ is an operator used to request for memory allocation.

 

If memory is free,

• new operator initializes memory and
• returns the address of new allocated space.

new syntax

pointer_var = new datatype;

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Difference between malloc and new

Lets see the difference between malloc and new in c++.

Serial No.	malloc()	new
1	malloc() doesn’t call constructor	new calls constructor
2	malloc() is a function	new is a operator
3	malloc() returns void pointer	new returns same data type
4	On failure condition it returns NULL	It returns bad_allocation