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malloc() vs new

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Following are the differences between malloc() and operator new.

  1. Calling Constructors: new calls constructors, while malloc() does not. In fact primitive data types (char, int, float.. etc) can also be initialized with new. For example, below program prints 10.


using namespace std;
int main()
    // Initialization with new()
    int *n = new int(10);
    cout << *n;
    return 0;




2. operator vs function: new is an operator, while malloc() is a function.

3. return type: new returns exact data type, while malloc() returns void *.

4. Failure Condition: On failure, malloc() returns NULL where as new throws bad_alloc exception.

5. Memory: In case of new, memory is allocated from free store where as in malloc() memory allocation is done from heap.

6. Size: Required size of memory is calculated by compiler for new, where as we have to manually calculate size for malloc().

7. Buffer Size: malloc() allows to change the size of buffer using realloc() while new doesn’t

calls constructordoes not calls constructors              
It is an operatorIt is a function
Returns exact data typeReturns void *
on failure, Throws bad_alloc exception     On failure, returns NULL
size is calculated by compilersize is calculated manually

Please write comments if you find anything incorrect in the above post, or you want to share more information about the topic discussed above.

Last Updated : 08 Jul, 2021
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