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Confused about use * in declaring char arrays
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I'm confused about the use of the dereference operator in the declaring of char arrays.
I think I understand that the dereference operator is used to dereference memory addresses to their values, and also in an unrelated function in the declaration of pointers; and that arrays are like special pointers to memory addresses.
But why is the * operator used in declaring char arrays, e.g.:
Why doesn't the following work, and instead give a series of "invalid conversion from `const char*' to `char'" errors?:
Why are char arrays different than say int arrays?
I think I understand that the dereference operator is used to dereference memory addresses to their values, and also in an unrelated function in the declaration of pointers; and that arrays are like special pointers to memory addresses.
But why is the * operator used in declaring char arrays, e.g.:
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Originally Posted by Kadence 
I'm confused about the use of the dereference operator in the declaring of char arrays.
I think I understand that the dereference operator is used to dereference memory addresses to their values, and also in an unrelated function in the declaration of pointers; and that arrays are like special pointers to memory addresses.
But why is the * operator used in declaring char arrays, e.g.:
Why doesn't the following work, and instead give a series of "invalid conversion from `const char*' to `char'" errors?:C++ Syntax (Toggle Plain Text)
Why are char arrays different than say int arrays?C++ Syntax (Toggle Plain Text)
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Ah I see, yes that works.
However I still don't understand the use of the * operator in the context of declaring arrays.
However I still don't understand the use of the * operator in the context of declaring arrays.
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Some arrays...
A char array (and only char arrays), can also be initialised like this (for convenience)
Finally, also for char only, is a pointer to a string constant
A pointer to a string constant is like this to the compiler. the only difference being is that you never get to see the anonymous name the compiler generates.
Again, this is a programmer convenience which only applies to char.
If you wanted say a pointer to an integer constant, then you would have to do that the long way by yourself.
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A char array (and only char arrays), can also be initialised like this (for convenience)
char arr[ ] = "123"; Finally, also for char only, is a pointer to a string constant
char *arr = "123"; A pointer to a string constant is like this to the compiler.
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Again, this is a programmer convenience which only applies to char.
If you wanted say a pointer to an integer constant, then you would have to do that the long way by yourself.
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I think you need to learn how to use pointers. Heres a tutorial:
You probably only need to look at the Pointer initialization section.
http://www.cplusplus.com/doc/tutorial/pointers.html
You probably only need to look at the Pointer initialization section.
http://www.cplusplus.com/doc/tutorial/pointers.html
Last edited by William Hemsworth; May 29th, 2008 at 8:10 am.
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Originally Posted by Salem
A char array (and only char arrays), can also be initialised like this (for convenience)
char arr[ ] = "123";
Finally, also for char only, is a pointer to a string constant
char *arr = "123";
A pointer to a string constant is like this to the compiler.
Is there any programming reason why I always see function definitions with arguments like this:
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Posting Whiz in Training
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Originally Posted by Kadence
Is there any programming reason why I always see function definitions with arguments like this:
Instead of this?:C++ Syntax (Toggle Plain Text)
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Originally Posted by Kadence
Also this code:
Didn't work for me, it gives a " invalid conversion from `const char*' to `char*'" compile error.C++ Syntax (Toggle Plain Text)
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Originally Posted by Kadence
Would it be correct to say that char *arr = "123"; is like this to the compiler:
Without the constant declaration?C++ Syntax (Toggle Plain Text)
By the way, when you use string literals, you should always make it "const char *", even though the compiler doesn't force you to make it const. This is because they are usually stored in a read-only part of memory.
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> Didn't work for me, it gives a " invalid conversion from `const char*' to `char*'" compile error.
> Would it be correct to say that char *arr = "123"; is like this to the compiler:
The ability to do
Some time ago, a change was added to the standards to allow"string" constants to be placed in read-only memory (and thus const). But they don't have to be. Another thing the standards people try to do is avoid breaking existing common practice in existing code.
Any new code, and any code being maintained should be writing
For the moment, you can get away with it, but you should really start using const to be future-proof.
> Would it be correct to say that char *arr = "123"; is like this to the compiler:
The ability to do
char *arr = "a string"; is a special case relaxation of the rules. In other situations, the compiler will tell you whether you're breaking 'const-correctness'.Some time ago, a change was added to the standards to allow"string" constants to be placed in read-only memory (and thus const). But they don't have to be. Another thing the standards people try to do is avoid breaking existing common practice in existing code.
Any new code, and any code being maintained should be writing
const char *arr = "a string"; For the moment, you can get away with it, but you should really start using const to be future-proof.
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