PowerBuilder Developing a simple calculator

The simple calculator refers to the user each input complete expression (one yuan or two yuan) calculates.

1, design a good interface

2. define three variables in declare Instance variable

Decimal ADD1//storage operand
Char S1//store operator
int flag//Determine if the calculation is complete

3. Double-click on the value and decimal keys to add clicked () function contents

If Flag=0 then sle_1.text= ""        flag=1     End If      sle_1.text=sle_1.text+this.text

4. Add the contents of the clicked () function within four operators

Choose case  S1    case  ' * '        sle_1.text=string (Dec (sle_1.text) *add1)          //dec (x) function is to convert the X value to a numeric type          the role of the//string (x) function is to convert the X value to the character case    '/'        sle_1.text=string (Add1/dec (sle_1.text)) Case  ' + '        sle_1.text=string (Dec (sle_1.text) +add1) Case    '-'        sle_1.text=string (Add1-dec (sle_1.text))  End Choose   Add1=dec (Sle_1.text)      //Keep the first input or intermediate result   s1=this.text              //Keep the operator just pressed   flag=0                    //Prepare to enter next number

5. Add the clicked () function contents to the equals sign

Choose case  S1 case        ' * '          sle_1.text=string (Dec (sle_1.text) *add1) Case        '/'          sle_1.text=string ( Add1/dec (sle_1.text) Case        ' + '          sle_1.text=string (Dec (sle_1.text) +add1) Case        '-'          sle_1.text= String (Add1-dec (sle_1.text))     end Choose     flag=0     s1= "

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PowerBuilder Developing a simple calculator