Interview questions

[james]

Hi there,

Can anyone explain what's the difference between:

const * char
* const char
const * const char

thanks,
james

 

[Victor Bazarov]

Can anyone explain what's the difference between:

const * char
* const char
const * const char

All are syntax errors. The difference is in typing.

Real C++ declarations could be

char const * p1; // a pointer to a constant char
const char * p2; // the same as above
char * const p3; // a constant pointer to a char
char const * const p4; // a constant pointer to a constant char.

V

 

[Thomas Matthews]

Hi there,

Can anyone explain what's the difference between:

const * char
* const char
const * const char

thanks,
james

This is discussed in detail in the C++ FAQ:
http://www.parashift.com/c++-faq-lite/const-correctness.html
One should always consult the FAQ before posting.

--
Thomas Matthews

C++ newsgroup welcome message:
http://www.slack.net/~shiva/welcome.txt
C++ Faq: http://www.parashift.com/c++-faq-lite
C Faq: http://www.eskimo.com/~scs/c-faq/top.html
alt.comp.lang.learn.c-c++ faq:
http://www.raos.demon.uk/acllc-c++/faq.html
Other sites:
http://www.josuttis.com -- C++ STL Library book

 

[jeffc]

All are syntax errors. The difference is in typing.

Real C++ declarations could be

char const * p1; // a pointer to a constant char
const char * p2; // the same as above
char * const p3; // a constant pointer to a char
char const * const p4; // a constant pointer to a constant char.

On my compiler, p3 and p4 are part of illegal definitions because they don't
provide initialization.

 

[jeffc]

On my compiler, p3 and p4 are part of illegal definitions because they don't
provide initialization.

Which leads me to a question (never have been totally sure about this sort
of thing.) If you write
char const * const p4 = 0;
what have you initialized exactly, and if a compiler requires initialization
of const items, why is only 1 initialization required here?

 

[Jeff Schwab]

Which leads me to a question (never have been totally sure about this sort
of thing.) If you write
char const * const p4 = 0;
what have you initialized exactly, and if a compiler requires initialization
of const items, why is only 1 initialization required here?

You've initialized a variable of type "pointer to constant char." No
char has been defined.

 

[Jeff Schwab]

I see your point taht no char has been defined, but you mean "constant
pointer to constant char", right?

Yes, you're exactly right. Sorry for the omission!

 

[jeffc]

You've initialized a variable of type "pointer to constant char." No
char has been defined.

I see your point taht no char has been defined, but you mean "constant
pointer to constant char", right?

 

[Victor Bazarov]

On my compiler, p3 and p4 are part of illegal definitions because they don't
provide initialization.

If the declarations are part of a class definition, there can be no
initialiser.

V