Hi all,

Can anyone explain me about make out of Structure and Union in C.

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Regards,
VELHARI
I am not totally useless. I can be used for a bad example

Hi,
Let me explain u about Structure and Union

Structure
=======
Structure is a collection of elements having different datatypes
For eg..
Struct a
{
int b[5]; //->Memory allocated(10)
char c;//->Memory allocated(1)
};

Structure ends with semicolon...
Here the declaration tells that
'a'->Structure Variable
b[5]->b is a structure element that can hold 5-elements of same datatype[int]..(i.e., it can store 5-Integer Element)
c->character element..
For b[5]->10-bytes are allocated,c->'1-byte is allocated.
Totally for structure variable 'a'->11-bytes are allocated..
For each element separate memory is allocated..

But in Union,
Union c
{
int b;
char c;
};

Here it takes the variable of largest datatype and assign that single memory for all union elements..
i.e.,For union variable 'c' it allocates the total of 2-bytes both for element 'b' and 'c'.(i.e.,Refer same Memory location ,No individual memory for each variable)
This is the main difference between Union and Structure.

hi velhari,

Structure is a collection of memory block, of different data type, in which it will have separate memory space for each data type.
Structure Definition
where as Union is a memory block where it has only one common memory space in which we can store any data but only one data at at time. (since every data share one common memory space, we can store only on data at a time)

UNion Definition

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SeeSamJagan
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