• Heinz <billgates microsoft.com> Jan 09 2007
• Kirk McDonald <kirklin.mcdonald gmail.com> Jan 09 2007
• Bill Baxter <dnewsgroup billbaxter.com> Jan 09 2007
• Frits van Bommel <fvbommel REMwOVExCAPSs.nl> Jan 10 2007

Heinz <billgates microsoft.com> writes:

Hi,

I just wan't to know the differences between 'alias' and 'typedef' as both do
the same thing.

Thanks

Kirk McDonald <kirklin.mcdonald gmail.com> writes:

Heinz wrote:
 Hi,
 
 I just wan't to know the differences between 'alias' and 'typedef' as both do
 the same thing.
 
 Thanks


Aliases provide another name for an existing type. Typedefs declare a 
new type which happens to be identical to an existing type. This can 
matter in function overloading, for instance:

alias int IntAlias;
typedef int IntTypedef;

void foo(int i) { }      // #1
void foo(IntAlias i) { } // #2 ERROR: Ambiguous with #1
void foo(IntTypedef i) { } // #3 Okay

void main() {
     int i = 1;
     IntAlias j = 2;
     IntTypedef k = 3;

     foo(i); // ERROR: Call #1 or #2?
     foo(j); // ERROR: Call #1 or #2?
     foo(k); // Okay, call #3
}

-- 
Kirk McDonald
Pyd: Wrapping Python with D
http://pyd.dsource.org

Bill Baxter <dnewsgroup billbaxter.com> writes:

Heinz wrote:
 Hi,
 
 I just wan't to know the differences between 'alias' and 'typedef' as both do
 the same thing.


I think the spec is pretty clear:
http://www.digitalmars.com/d/declaration.html#typedef

Have you read that yet?

--bb

Frits van Bommel <fvbommel REMwOVExCAPSs.nl> writes:

Bill Baxter wrote:
 Heinz wrote:
 Hi,

 I just wan't to know the differences between 'alias' and 'typedef' as 
 both do
 the same thing.


 I think the spec is pretty clear:
 http://www.digitalmars.com/d/declaration.html#typedef
 
 Have you read that yet?


And read the next few sections too.
For example, nobody has yet mentioned that alias is useful for more than 
just types.