Slide 8.4: Line-by-line anatomy of Forms.c   Slide 8.6: Line-by-line anatomy of Forms.c (cont.)   Home

Line-by-line Anatomy of Forms.c (Cont.)

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fld = (FieldPtr) FrmGetObjectPtr ( FrmGetActiveForm( ), obj );
The function void *FrmGetObjectPtr( const FormType *formP, UInt16 objIndex ) returns a pointer to the data structure of an object in a form.

• formP: Pointer to the form object (FormType structure)
• objIndex: Index of an object in the form. You can obtain this by using FrmGetObjectIndex( ).

h = (VoidHand) FldGetTextHandle( fld );
The function MemHandle FldGetTextHandle( const FieldType *fldP ) returns a handle to the block that contains the text string of a field or NULL if no handle has been allocated for the field pointer.

fldP: Pointer to a field object (FieldType structure)

h = MemHandleNew( FldGetMaxChars( fld )+10 );
This function UInt16 FldGetMaxChars( const FieldType *fldP ) returns the maximum number of bytes the maxChars field in FieldType accepts.

fldP: Pointer to a field object (FieldType structure)

The function MemHandle MemHandleNew( UInt32 size ) allocates a new movable chunk in the dynamic heap and returns a handle to it, or 0 if unsuccessful.

size: The desired size of the chunk

ErrFatalDisplayIf( !h, "No Memory" );
The macro #define ErrFatalDisplayIf( condition, msg ) displays an error alert dialog if condition is true and error checking is set to partial or full.

• condition: A boolean value. If true, display the error.
• msg: Error message text as a string