Function pointers

This is a discussion on Function pointers within the C++ Programming forums, part of the General Programming Boards category; I keep on getting this error in BCC32 Error E2285 a3main.cpp 149: Could not find a match for 'TextField::TextField(int ,int,int,char ...

  1. #1
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    Oct 2003
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    4

    Function pointers

    I keep on getting this error in BCC32

    Error E2285 a3main.cpp 149: Could not find a match for 'TextField::TextField(int
    ,int,int,char *,int,void,Field *)' in function mainScreen::mainScreen()

    and on the Unix AIXC:

    "a3main.cpp", line 137.18: 1540-0286 (W) The unqualified member "isName" should be qua
    lified with "::" and preceded by an "&" when forming an expression with type pointer-t
    o-member.
    "a3main.cpp", line 137.18: 1540-0216 (S) An expression of type "bool (mainScreen::*)(T
    extField *, Field *)" cannot be converted to "bool (*)(TextField *, Field *)".

    basically due to this code:
    Code:
    class mainScreen{
    
        //record r1;
    	//to keep track of number of records
    	int recordCount;
        fstream _f;
        streampos end;
    	Screen _mainS;
        enum{ ID,Name,A1,A2,A3,Mid,Final,Letter,Comments,Overall,Active1,Active2,Active3,Active4,Active5};
        int _flds[15];
        int _msgs[9];
    	Field msgField;
    	TextField txtStudId;
        //The Client does not need to access the list
    	struct node
    	{
    		record r;
    		int recNumb;//so the student record number will be known
    		node *next;
    		node *prev;
    
    		node(record n,int rn,node *nn=NULL,node *pn=NULL):r(n),recNumb(rn),next(nn),prev(pn){}
    	};
    	
    	node *Records;
    	//The current record
    	node *currentRecord;
    	//if update is true the text file is updating a record
    	//else it is just appending
    	bool writeToFile();
    	bool readFromFile();
    	//go to next node       
    	bool goNext();
    	bool goPrev();
    	void changeFields();
    	int search(bool SearchName);
    	double nV;
    	
    	void updateRecord();
    	//To get the Average grade per assignment/test and get the total of each
    	void getAverages(double *GradeList,int *CountList);
    	double calcGrade();
    		bool (*isValidN)(TextField *,Field *);
    		bool isName(TextField *txt, Field *msg);
    	public:
    		
    		mainScreen();
    		int edit();
    		
    
    		~mainScreen();
    		
    };
    /*create all the fields */
    mainScreen::mainScreen():msgField(24,2,70,""),txtStudId(4,15,10," ",9,isID,&msgField),Records(NULL){
    	
    	
    	....
    	
    	_mainS.addField(new Label(6,2,"Student Name: "));
    	_flds[Name]=_mainS.addField(new TextField(6,17,30,currentRecord->r.studName,30,isName,&msgField));
    --->The constructor takes a bool (*isValid)(TextField *,Field *) function pointer(this works when the function is not declared in the class, but I need to declare it inside to do something)
    	_msgs[Name]=_mainS.addField(new Field(7,2,30,""));
    	
    	}
    
    
    
    
    //Validation functions
    
    ...
    
    
    //checks name
    bool mainScreen::isName(TextField *txt, Field *msg) {
        bool ok = true;
        if (txt->getLength() == 0) {
    	ok = false;
    	if (msg != NULL) {
    	    msg->setData("Enter Student Name");
    	    msg->display();
    	}
        } else {
    	char *name = new char[txt->getLength() + 1];
    	txt->getData(name);
    	for(int i=0;name[i]!='\0';i++){
    		
    			if(i==0 && isalpha(name[i]) || name[i-1]==' ')
    				name[i]=toupper(name[i]);
    			else
    				name[i]=tolower(name[i]);
    			
    		}
    	txt->setData(name);
    	delete [] name;
        }
    	
        return ok;
    }
    ....
    
    
    int main()
    {
    	
    	mainScreen mS;
    	mS.edit();
    	
    	return 0;
    }
    any ideas would be appereciated, thank you
    Last edited by rmlove; 12-07-2003 at 09:41 AM.

  2. #2
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    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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  3. #3
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    thanks

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