App Inventor 2
Programming mobile phones with Android
by App Inventor 2 - Juan Antonio Villalpando
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46C.- Procedures with Do and Results. (III). Distance between two points in the plane.
ip46C_procedures_3
- Presentation
- Let's see Procedure with Results, to this we can also call functions. We supply some data and gives us a result.
- This we will see is a simple example of Procedure, could enter operations in the same block of Button1 and we would save the block of Procedure, it is simply a didactic example.
- Normally Procedures are used when a part of the code (eg operations) are needed in several blocks, imagine we have 8 - Button and each of them have to perform the operations, it would be easier to create a common block of operations through the procedure and call it from the various buttons, put all operations on all buttons.
- This is to introduce four data corresponding to the coordinates of two points P1(x1, y1) and P2(x2, y2), we call a Procedure called distance and we will result the distance between those two points that are in the same plane.
- The expression for calculation is:
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Design
distancia_puntos.png
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Blocks
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Comments
- When calling distance, we send the calculation parameters. The Procedure will return the result of that calculation.
- We have created a function called distance, which parameters we supply and return a result.
- If any of the data is entered, the application will fail for lack of data in solving the calculation.
- By Block "Is number?" that is in the part of Mathematics
it has to check, before calling distance if all the variables introduced are numbers.
- If any non - number, a message is displayed warning with Notifier , and operations are not performed.
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