New vs. Malloc( ): Know the Difference
By Shumaila Saeed & Hifza Nasir || Published on June 17, 2026
new is a C++ operator for dynamic memory allocation that also calls constructors, while malloc() is a C library function that allocates memory without initializing it.
Key Differences
In C++, new not only allocates memory on the heap but also initializes the memory by calling the object's constructor, providing type safety and automatic object initialization. malloc(), used in C, allocates a specified amount of memory but leaves it uninitialized, requiring explicit casting and manual object initialization in C++.
Hifza Nasir
Jun 17, 2026
new returns a pointer to the type it allocates, ensuring type safety and eliminating the need for casting, unlike malloc() which returns a void* pointer, necessitating explicit type casting in C++. This makes new more aligned with C++'s object-oriented features.
Shumaila Saeed
Jun 17, 2026
Memory allocated with new should be freed with delete, which also calls the object's destructor. Conversely, memory allocated with malloc() is deallocated using free() without calling destructors, making it less suited for C++ objects that require proper cleanup.
Shumaila Saeed
Jun 17, 2026
new can be overloaded to provide custom behavior for specific classes, offering flexibility in memory allocation and object initialization. malloc(), being a library function, does not provide this capability, limiting its utility in C++.
Dua Fatima
Jun 17, 2026
In case of allocation failure, new throws a bad_alloc exception (unless nothrow is specified), providing a mechanism for exception handling, while malloc() returns NULL, requiring manual error checking.
Dua Fatima
Jun 17, 2026
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Comparison Chart
Initialization
Initializes objects and calls constructors
Allocates uninitialized memory
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Jun 17, 2026
Type Safety
Type-safe, returns a typed pointer
Returns a void*, requires casting
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Jun 17, 2026
Deallocation
Paired with delete, calls destructors
Paired with free(), no destructors
Hifza Nasir
Jun 17, 2026
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New and Malloc( ) Definitions
New
Automatically calls the object's constructor.
MyClass* obj = new MyClass(); calls MyClass constructor.
Hifza Nasir
Feb 26, 2024
Malloc( )
Paired with free() for memory deallocation.
Free(ptr); releases the allocated memory.
Shumaila Saeed
Feb 26, 2024
New
Must be matched with delete for proper cleanup.
Delete ptr; deallocates memory and calls the destructor.
Hifza Nasir
Feb 26, 2024
Malloc( )
Returns NULL on allocation failure, requiring checks.
If (ptr == NULL) { /* Handle error */ }
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Feb 26, 2024
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New
Ensures type safety and eliminates casting.
Auto ptr = new double; directly returns a double*.
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Feb 26, 2024
Malloc( )
Requires manual object initialization.
*ptr = 5; initializes the allocated integer to 5.
Shumaila Saeed
Feb 26, 2024
New
Can throw exceptions on allocation failure.
Try { int* arr = new int[1000000000]; } catch (std::bad_alloc& e) { /* Handle error */ }
Shumaila Saeed
Feb 26, 2024
Malloc( )
Returns void* requiring explicit casting in C++.
Double* ptr = (double*)malloc(sizeof(double));
Hifza Nasir
Feb 26, 2024
New
Allocates and initializes memory for C++ objects.
Int* ptr = new int(5); allocates an integer and initializes it to 5.
Shumaila Saeed
Feb 26, 2024
Malloc( )
Allocates uninitialized memory, primarily used in C.
Int* ptr = (int*)malloc(sizeof(int)); allocates space for an integer.
Hifza Nasir
Feb 26, 2024
Repeatedly Asked Queries
Why prefer new over malloc() in C++?
new provides type safety, object initialization, and exception handling, aligning with C++'s object-oriented features.
Hifza Nasir
Jun 17, 2026
Can malloc() be used for allocating objects in C++?
While possible, malloc() does not call constructors, making it unsuitable for objects that require initialization.
Hifza Nasir
Jun 17, 2026
Is it possible to use both new and malloc() in the same C++ program?
Yes, but it's not recommended due to differences in initialization, type safety, and cleanup requirements.
Shumaila Saeed
Jun 17, 2026
What happens if new fails to allocate memory?
new throws a bad_alloc exception, unless the nothrow variant is used, in which case it returns NULL.
Hifza Nasir
Jun 17, 2026
How does error handling differ between new and malloc()?
new throws a bad_alloc exception on failure, whereas malloc() returns NULL, necessitating manual error checking.
Shumaila Saeed
Jun 17, 2026
Why is type casting necessary with malloc() in C++?
malloc() returns a void*, so casting is necessary to convert it to the correct type pointer in C++.
Dua Fatima
Jun 17, 2026
How does delete differ from free()?
delete calls the destructor and deallocates memory, while free() simply deallocates memory without calling destructors.
Dua Fatima
Jun 17, 2026
Is there a performance difference between new and malloc()?
The performance may vary, but new could be slower due to constructor calls, though the difference is often negligible.
Dua Fatima
Jun 17, 2026
How to properly initialize an object allocated with malloc() in C++?
You must manually call the constructor using placement new, e.g., MyClass* obj = new(malloc(sizeof(MyClass))) MyClass();.
Shumaila Saeed
Jun 17, 2026
What is the nothrow variant of new?
It's a version of new that returns NULL instead of throwing an exception on allocation failure, e.g., int* ptr = new(std::nothrow) int;.
Hifza Nasir
Jun 17, 2026
What is the equivalent of malloc() for array allocation in C++?
C++ uses new[] for array allocation, e.g., int* arr = new int[10];, which also initializes the array elements if a constructor is available.
Dua Fatima
Jun 17, 2026
Why is malloc() still used in C++?
It's generally for compatibility with C code or for low-level memory management tasks that do not require object-oriented features.
Shumaila Saeed
Jun 17, 2026
How do you deallocate memory allocated with new and malloc()?
Use delete for memory allocated with new and free() for memory allocated with malloc().
Shumaila Saeed
Jun 17, 2026
Can new be used in C programs?
No, new is a C++ operator and is not available in C.
Shumaila Saeed
Jun 17, 2026
Can custom memory allocation be done with new?
Yes, new can be overloaded to provide custom memory allocation and initialization behavior for classes.
Shumaila Saeed
Jun 17, 2026
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About Author
Written by
Shumaila SaeedShumaila Saeed, an expert content creator with 6 years of experience, specializes in distilling complex topics into easily digestible comparisons, shining a light on the nuances that both inform and educate readers with clarity and accuracy.
Co-written by
Hifza Nasir
Hifza Nasir
Dua Fatima
Shumaila Saeed
