C2025 - Undeclared Identifier 'NULL'

This is a discussion on C2025 - Undeclared Identifier 'NULL' within the C++ Programming forums, part of the General Programming Boards category; Have the following abstract class, not sure why I am getting an error on the constructor Code: #ifndef __SCRIO_H #define ...

  1. #1
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    C2025 - Undeclared Identifier 'NULL'

    Have the following abstract class, not sure why I am getting an error on the constructor

    Code:
    #ifndef __SCRIO_H
    #define __SCRIO_H
    
    class IOScreen;
    
    class IOField
    {
    
    	private:
    			int row,
    				col;
    	protected:
    			void *data;
    			IOScreen *owner;
    			bool Ok;
    			void (*help)(IOScreen *scrPtr); 
    			bool (*isValid)(void *data, IOScreen *scrPtr);
    			int Row();
    			int Col();
    
    	public:
    			IOField(int row, int col, 
    				    void (*help)(IOScreen *) = NULL,
    					bool (*isValid)(void *, IOScreen *) = NULL);
    			virtual ~IOField();
    			virtual void display()=0;
    			virtual int edit()=0;
    			virtual void *getData();
    			bool failed();
    			virtual void clear();
    			IOScreen *getOwner;
    			void setOwner(IOScreen *owner);
    };
    #endif
    Code:
    error C2065: 'NULL' : undeclared identifier

  2. #2
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    Whoa dont tell me NULL is nonstandard, 0 works.

  3. #3
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    Jan 2005
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    7,340
    NULL is standard, although 0 is preferred.

    To use NULL, you have to include a header that defines it.

  4. #4
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    Nov 2004
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    93
    Alrighty, thanks

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