Softwareentwicklung in C++ - ASC

470 15. Verschiedenes
15.3 Funktionspointer
Wie bereits in Abschnitt 6.2.4 erwähnt, gibt es auch in C ++ die bereits
von C her bekannten Funktionspointer. Man kann einfach eine entsprechende
Pointervariable definieren und ihr als Adresse die Einsprungadresse
einer Funktion zuweisen. In C ++ kann man Funktionspointer allerdings
nicht nur auf Funktionen zeigen lassen, sondern unter anderem auch auf
Member-Methoden. Sehen wir uns hierzu einfach ein kleines Beispiel an
(function_pointer_demo1.cpp):
1 // function pointer demo1 . cpp − f i r s t demo f o r function p o i n t e r s
2
3 #include
4 #include ” u s e r t y p e s . h”
5
6 using std : : cout ;
7 using std : : endl ;
8
9 //−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−
10 uint32 aCalculationFunction ( uint32 val )
11 {
12 return ( val ∗ 5 ) ;
13 }
14
15 //−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−
16 uint32 anotherCalculationFunction ( uint32 val )
17 {
18 return ( val + 17);
19 }
20
21 //−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−
22 /∗
23 ∗ CalcMethodCollection
24 ∗
25 ∗ j u s t a dummy c o l l e c t i o n of c a l c u l a t i o n methods
26 ∗
27 ∗/
28
29 class CalcMethodCollection
30 {
31 private :
32 CalcMethodCollection ( ) ;
33 CalcMethodCollection ( const CalcMethodCollection &) {}
34 const CalcMethodCollection& operator = ( const CalcMethodCollection&)
35 { return (∗ this ) ; }
36 public :
37 //−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−
38 static uint32 aSpecialCalculationFunction ( uint32 val )
39 {
40 return ( val ∗ 2 ) ;
41 }
42
43 //−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−
44 static uint32 anotherSpecialCalculationFunction ( uint32 val )
45 {
46 return ( val + 12);
47 }
48 } ;
49
50
51 //−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−−
52 int main ( int argc , char ∗ argv [ ] )