The Boolean variable startFlag is set to True if a number has been entered and an operator button has been pressed, to indicate that a calculation is in progress and that a value has been assigned to firstTerm. The addition, subtraction, multiplication and division operators are referenced by the integer values 1, 2, 3 and 4 respectively. The integer variables activeOp and lastOp store numeric references to the operator most recently clicked and the operator previously clicked, if applicable. In an ongoing calculation, the number currently being entered by the user is stored in the variable secondTerm, and any value held in memory is stored in the variable memory. The Boolean variables opFlag, eqFlag and funcFlag are used to determine whether the user has clicked on any of the operator buttons (" +", " -", " *", or " /"), the equals button (" ="), or a function button (" ±", " √", " 1/x" or " %").ĭouble-precision floating point variables are used to store numeric input and results. The integer variables charLimit and inputLength are used to keep track of the number of characters allowed for the current input string, and the number of characters entered by the user, at any given time.
#Vb calculator source code code
The program presented in this section makes use of this feature to enable a single event handler to handle the Click event for all of the button controls for a simple calculator application. By contrast, we can now assign the same event handler to the Click event of any number of controls on a form, even if they are not all of the same type. For example, a control array in Visual Basic 6 could only include controls of one type. Although things are no longer quite so straightforward in this respect, Visual Basic now has features that provide more flexibility to the programmer.
Ultimately, one had to accept that VB.Net was very different to Visual Basic 6, and adopt a new way of working.ĭespite the demise of the control array, it is still possible to manage a related group of objects as if they were members of an array. Many methods were suggested for creating control arrays programmatically, and the subject continued to generate controversy. Indeed, Microsoft subsequently declared these classes to be obsolete.Ī lively debate ensued between developers over whether or not control arrays should have been omitted from the. Microsoft also provided a number of "control array compatibility classes" that could be added to the VB.Net toolbox, but at the same time advised developers not to use them as they could not guarantee continued support in future versions of VB.Net. However, since one of the attractions of Visual Basic in the past has been that it is an easy programming language for new programmers to learn, this was not an ideal solution. Microsoft provided a workaround that involving writing some rather inelegant-looking and complex code in order to create an array of controls at run time.
#Vb calculator source code upgrade
One of the main complaints was that existing VB6 applications that employed control arrays were difficult to upgrade to VB.Net.
Microsoft abandoned control arrays with VB.Net, somewhat to the chagrin of a large number of VB6 developers. If one button in an array of button controls was clicked, the control's array subscript was passed to the event handler, which would determine which button had been clicked and take the required action for that button.įrom the programmer's point of view, the ability to create control arrays at design time by simply copying an existing control and pasting it onto the form as many times as required was an attractive feature of Visual Basic 6. Like other array variables, each member of a control array had an array subscript by which it could be referenced. In real terms, a control array was actually a collection of controls that could be programmed as an array thanks to some fairly complex behind-the-scenes code provided by Microsoft. Before VB.Net arrived in 2002, the highly popular Visual Basic 6 provided programmers with the ability to create what were known as control arrays.
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