C++ - Memory Allocation

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Memory Allocation

How much memory is allocated with the statements below?
(i) short* ps = (short*) malloc (100);
(ii) short* ps = (short*) new short (100);

Total Answers and Comments: 4

Last Update: September 08, 2009 Asked by: prettyfox

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Best Rated Answer

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Submitted by: rocky2583

The first statement
short* ps = (short*) malloc (100);
will allocate 100 bytes of memory.

while the second statement
short* ps = (short*) new short (100);

will allocate (assuming short is 2 bytes) 200 bytes of memory.

There is no need to typecast the pointer returned by new operator, coz new automatically returns pointer to desired type, unlike malloc which returns void pointer.

Above answer was rated as good by the following members:
yzesong, j_l_larson, thumbeti

July 19, 2008 13:52:40

rocky2583

Member Since: July 2008 Contribution: 3

RE: Memory Allocation

The first statement
short* ps (short*) malloc (100);
will allocate 100 bytes of memory.

while the second statement
short* ps (short*) new short (100);

will allocate (assuming short is 2 bytes) 200 bytes of memory.

There is no need to typecast the pointer returned by new operator coz new automatically returns pointer to desired type unlike malloc which returns void pointer.

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September 29, 2008 02:37:09

hrisheekesh.kale27

Member Since: September 2008 Contribution: 4

RE: Memory Allocation

The first statement will allocate 100 bytes.

The second one will allocate 2 bytes (one short) and call the constructor with arg as 100.

This will initialize the memory to 100.

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December 07, 2008 09:22:07

burraganesh

Member Since: December 2008 Contribution: 20

RE: Memory Allocation

The first statement will allocate 100 bytes on heap the memory locations will have garbage values.

The second statement will allocate 2 bytes on heap and initialise the allocated region with 100.

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September 08, 2009 07:32:38

k.senthilvelan

Member Since: September 2009 Contribution: 1

RE: Memory Allocation

short* ps (short*) malloc (100);
malloc will allocate 100 bytes and then convert it to short type...

short* ps1 (short*) new short (100);
this creates a memory of size short and assign the value 100 to *ps1.

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