DWORD dw='pp' is valid in VC++ 6.0 :(

Raj Prathap

I'm using VS6.0. I was going through the code which was written nearly 3 years before. I have seen one statement like said in the subject DWORD dw='pp'; I was not aware that is a valid statement. And still I'm not clear what will be the value of dw. I calculated if it is equivalent to ('p'<<8 + 'p') but no success. Can some kindly clarify me on whether two characters in single cotes is valid in C/C++ or it is valid only in VC++. If valid in VC++, how would the value is calculated for the literal in two cotes. regards, Pratap

toxcct

'pp' is not a valid character, but AFAIK, it is understood as if it were the first character written solely : 'p' so, you DWORD contains the ascii code of 'p', chis is 112 (0x00000070)

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Raj Prathap

No! The DWORD value is coming as 28784 in my machine

toxcct

so, that is 0x7070... strange, but quite logical if we know that 'p' is 0x70

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Raj Prathap

I'm sorry There was a mistake in calculating the value of 0x7070 in decimal format. The value is 0x7070 only!! Thanks a lot for your support!! could you kindly specify that the statement DWORD dw='pp'; is valid in all platforms!! I'm googling for it, but no success!!

Nishad S

Raj Prathap wrote:

was not aware that is a valid statement.

It is a valid statement.

Raj Prathap wrote:

And still I'm not clear what will be the value of dw.

DWORD is four bytes long. The higher two bytes will be 0 and the lower two bytes will be the value 'p'. Like 0x00007070. And if it was 'pa' then value would be 0x00007061. Also upto 4 characters are possible. For example dw = 'abcd' means 0x61626364.

Raj Prathap wrote:

I calculated if it is equivalent to ('p'<<8 + 'p') but no success.

The problem caused with your code is the precedence of operators. Try DWORD dw = ( 'p' << 8 ) + 'a';

- NS -

CPallini

toxcct wrote:

'pp' is not a valid character,

it is a valid (though discouraged) multicharacter constant, see [^].

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David Crow

Raj Prathap wrote:

DWORD dw='pp'; I was not aware that is a valid statement.

It is, because 'pp' is treated as an int, and since it is being assigned to a DWORD, all is well. Had you tried to assign it to a char instead, one of the letters (I can't recall which way it works) would have been dropped.

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Raj Prathap

Sorry for replying after so many days.. it was Deevali in India and I was in vacation. Thanks a lot for the link. It was quite helpful. Pratap

CPallini

:-D

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