C + + callback

C + + callbacks contain class function callbacks and non-class function callbacks.

Class function callback, the function pointer points to the function name, need to take the class scope, call to use the class pointer.

Like QT, define a function pointer with a return value of Qbytearray.

typedef qbytearray (Mythead::* func_construct) (Qbytearray line);//Defining function PointersQbytearray devicestatus_construct (Qbytearray);    Qbytearray realdata_construct (Qbytearray line);    Qbytearray dayrun_construct (Qbytearray);    Qbytearray monthcheck_construct (Qbytearray line);    Qbytearray flag_construct (Qbytearray line);    Qbytearray palarm_construct (Qbytearray line);    Qbytearray devicedefine_construct (Qbytearray line);    Qbytearray staff_construct (Qbytearray line);   Qbytearray Devicestatus_construct_str (QString line);  CaseE_devicestatus:pfunc= &mythead::d evicestatus_construct;  Break;  CaseE_realdata:pfunc= &mythead::realdata_construct;  Break;  CaseE_dayrun:pfunc= &mythead::d ayrun_construct;  Break;  CaseE_monthcheck:pfunc= &mythead::monthcheck_construct;  Break;  CaseE_flag:pfunc= &mythead::flag_construct;  Break;  CaseE_palarm:pfunc= &mythead::p alarm_construct;  Break;  CaseE_devicedefine:pfunc= &mythead::d evicedefine_construct;  Break;  CaseE_staff:pfunc= &mythead::staff_construct; callback: Qbytearray btline= ( This->*pfunc) (Strline.toutf8 ());

Non-class pointers are much simpler:

1typedefvoid(*func) (int,int )2 voidFunc1 (intNumaintNumB) {3printf (numa+NumB); 4 }5 6 voidFunc2 (intNumaintNumB) {7printf (NumA-NumB); 8 }9 Ten intMain () { One      intNumA =Ten; A     intnumb=5;  -Func PFunc = &func1; - PFunc (NumA, NumB); thePFunc = &Func2; - PFunc (numa,numb); - Return0; -}

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C + + callback