C - What will be difference b/w 5th and 6th statements?

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What will be difference b/w 5th and 6th statements?

1. #define MAX 100
2. main()
3. {
4. int max=100;
5. int a[MAX];
6. int b[max];
7. }

Total Answers and Comments: 5

Last Update: July 14, 2009 Asked by: Pramoda.M.A

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Best Rated Answer

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Submitted by: vinayps03

Size of an array can't be dynamically resized at runtime (one of the reasons y v use data structures!)
5th line: size of a[MAX] is constant (100) --> so no probs here.
6th line: Compilation error..
c:Code(6) : error C2057: expected constant expression

c:Code(6) : error C2466: cannot allocate an array of constant size 0

c:Code(6) : error C2133: 'b' : unknown size

Above answer was rated as good by the following members:
sourabh_t

August 06, 2008 16:13:59

vinayps03

Member Since: August 2008 Contribution: 1

RE: What will be difference b/w 5th and 6th statements?

c:Code(6) : error C2466: cannot allocate an array of constant size 0

c:Code(6) : error C2133: 'b' : unknown size

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Overall Rating: +1

August 07, 2008 03:20:58

kalai4best

Member Since: August 2008 Contribution: 2

RE: What will be difference b/w 5th and 6th statements?

max can be used only within the main() and has a impact within that. But MAX can be used in any kind of user defined functions.

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September 19, 2008 03:17:19

mayankjaan

Member Since: September 2008 Contribution: 1

RE: What will be difference b/w 5th and 6th statements?

On 5th statement work fine.

But on 6 the statement it gives compilation error.

error C2057: expected constant expression

error C2466: cannot allocate an array of constant size 0

error C2133: 'b' : unknown size

Conclusion:

The macro value expansion done at compilation time but the assignment of
variable value at run time.

Also the array has property to assign constant value not and variable value

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July 04, 2009 16:56:27

abhimanipal

Member Since: July 2009 Contribution: 22

RE: What will be difference b/w 5th and 6th statements?

It wont give any compile time bugs. It will compile just fine ..

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July 14, 2009 11:52:33

vinodkumar_garg

Member Since: June 2009 Contribution: 3

RE: What will be difference b/w 5th and 6th statements?

5th statement here the array size will be assigned at preprocessor stage.

6th statement here it will not give any compile time error but some the program will be having lot of bugs. size will be assigned at run time.

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