Msg Box Function Displays one of Visual Basics

Msg. Box Function • Displays one of Visual Basic’s predefined dialog boxes, which contains a message, one or more command buttons, and an icon • After displaying the dialog box, the Msg. Box function waits for the user to choose a button, then returns a value that indicates which button the user selected

Msg. Box Function • Syntax: Msg. Box(prompt[, buttons][, title][, helpfile, context]) • prompt is the message you want displayed • buttons is a numeric expression that specifies the number and type of buttons, the icon, the default button, and the modality • title is a string expression displayed in the title bar

buttons Argument Constant vb. OKOnly vb. OKCancel vb. Abort. Retry. Ignore vb. Yes. No. Cancel vb. Yes. No vb. Retry. Cancel vb. Critical vb. Question vb. Exclamation vb. Information vb. Default. Button 1 vb. Default. Button 2 vb. Default. Button 3 vb. Default. Button 4 vb. Application. Modal Value 0 1 2 3 4 5 16 32 48 64 0 256 512 768 0 vb. System. Modal 4096 Description Display OK button only. Display OK and Cancel buttons. Display Abort, Retry, and Ignore buttons. Display Yes, No, and Cancel buttons. Display Yes and No buttons. Display Retry and Cancel buttons. Display Critical Message icon. Display Warning Query icon. Display Warning Message icon. Display Information Message icon. First button is default. Second button is default. Third button is default. Fourth button is default. Application modal; the user must respond to the message box before continuing work in the current application. System modal; all applications are suspended until the user responds to the message box.

Return Values Constant vb. OK vb. Cancel vb. Abort vb. Retry vb. Ignore vb. Yes vb. No Value 1 2 3 4 5 6 7 Description OK Cancel Abort Retry Ignore Yes No

Keyboard Processes

Low Level Keyboard Handlers • Three events recognized by forms and any control that accepts keyboard input – Key. Down - As any key is pressed – Key. Up - as any key is released – Key. Press -When any ASCII Character key is pressed • Only the object that has the focus can accept a key event • A Form has the focus only if the form is active and no control on the form has the focus

Key. Press Event • Is passed only the integer ASCII equivalent of the key pressed and no other information. • Not all keys generate a Key. Press event - only those which have an ASCII equivalent – numbers, letters, punctuation, BACKSPACE, TAB, Ctrl-a through Ctrl-z, Ctrl-[, Ctrl-], Ctrl-BACKSPACE – ESC (unless there is a command button with Cancel = True) – ENTER (unless there is a command button with Default = True) • For example, to force all characters in a textbox to be uppercase as entered: Private sub text 1_keypress(Key. Ascii as Integer) Key. Ascii = Asc(Ucase(Chr(Key. Ascii))) end Sub

Key. Down and Key. Up Events • Different from keypress in a similar way that mouseup/down is different from the click event • Key. Up/Down report the exact physical state of the keyboard itself • You must interpret what that state represents – example: Key. Press treats a and A as two separate characters, returning different codes. The Key. Up/Down will return the same code for both. • Exceptions – – ESC if there is a command button with Cancel = True ENTER if there is a command button with Default = True TAB Any key for which a menu Shortcut key has been defined

Key. Down and Key. Up Events (2) • The Key. Up/Down events receive two arguments – keycode - indicates the physical key pressed • a and A are the same Key and return the same code • 2 on the typewriter keypad and 2 on the numeric keypad are different keys and return different codes • Use the vb. Constants to refer to them (use the Object Browser). For example: vb. Key 2, vb. Key. Home, vb. Key. Numpad 2 • keycodes for the letter keys are the same as the ANSI codes of the uppercase letter • keycodes for the number and punctuation keys are the same as the ANSI code of the number on the key

Key. Down and Key. Up Events (3) – Shift - almost the same as Shift for mouse events with the value • • 1 indicating the Shift key was depressed 2 indicating the Ctrl key was pressed 4 indicating the Alt key was pressed All 8 combinations are possible (0 -7)

Option Buttons • Used in situations where you want to limit the user to only one of two or more related and mutually exclusive choices. • Only one in a group can be selected (on) at any one time. • When selected, an option button’s Value property contains the Boolean value True; otherwise it contains the Boolean value False.

Option Buttons • • • Minimum number in an interface is two Recommended maximum number is seven Use sentence capitalization for the caption Assign a unique access key A default button should be selected when the interface first appears.

Option Buttons • You must use a frame control if you want the interface to contain more than one group of option buttons • Set the Tab. Index property of the option buttons in each group so that the user can use the up and down arrow keys to select another button in the group.

Frame Control • Acts as a container for other controls • Used to visually separate controls from one another • The frame and the controls contained within the frame are treated as one unit • You must use a frame control if you want to have more than one group of option buttons • Use sentence capitalization for the optional caption

Check Box • Used in situations where you want to allow the user to select any number of choices from one or more independent and non-exclusive choices. • Any number of check boxes can be selected at any one time. • When selected, a check box’s Value property contains the number 1 (vb. Checked). When unselected, it contains the number 0 (vb. Unchecked).

Check Box • Use sentence capitalization for the check box’s Caption • Assign a unique access to each check box • You also can use the spacebar to select/deselect a check box that has the focus