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The dictionary is printed in Listing 2 producing the output shown in Figure 1 .
| Listing 2 . Scan for available stations. |
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#Program the three buttons labeled 1, 2, and 3
#First scan for available stationsradio01Stations = radio01.scan("Austin")
print("Available stations in Austin")print(radio01Stations) |
As mentioned above, Figure 1 shows the output produced by the code in Listing 2 .
| Figure 1 . Output from the code in Listing 2. |
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Available stations in Austin
{93.7: 'KLBJ', 91.7: 'KVRX', 98.1: 'KVET', 95.5: 'KKMJ'} |
This program simulates a radio having three station-selector buttons. The code in Listing 3 uses the object's reference stored in radio01 to call a method named setStationNumber three times in succession on the object to program each of the three buttons to the frequencies shown. (Note that the buttons are numbered 1, 2, and 3 instead of 0, 1, and 2.)
| Listing 3 . Program the buttons on radio01. |
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print("Program the buttons")
radio01.setStationNumber(1,radio01Stations[91.7])
radio01.setStationNumber(2,radio01Stations[95.5])
radio01.setStationNumber(3,radio01Stations[98.1]) |
The output produced by the code in Listing 3 is shown in Figure 2 .
| Figure 2 . Output from the code in Listing 3. |
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Program the buttons |
Now that our favorite radio stations in the local area (Austin) have been programmed into the buttons, we can play any of the three stationssimply by turning the radio on and pressing a station-selector button.
Listing 4 calls the playStation method three times in succession on the radio01 object to simulate pressing each of the three buttons. This program doesn't actually produce sound.Instead, it simulates playing a radio station by printing a message identifying the call sign of the station being played.
| Listing 4 . Play the three programmed stations. |
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print("Play the three programmed stations")
radio01.playStation(3)radio01.playStation(2)
radio01.playStation(1) |
Figure 3 shows the output produced by the code in Listing 4 .
| Figure 3 . Output from the code in Listing 4. |
|---|
Play the three programmed stations
Playing KVETPlaying KKMJ
Playing KVRX |
As I explained earlier, once a class definition is available, it can be used to instantiate any number of objects. This is illustrated in Listing 5 , which simulates the manufacturing, programming, and playing of a different radioobject.
As you can see in Listing 5 , the buttons on this radio are programmed for stations in Dallas suggesting the owner of this radio livesin Dallas.
| Listing 5 . Manufacture another 3-button radio. |
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#Manufacture another 3-button radio
radio02 = Radio()#Program the three buttons labeled 1, 2, and 3
#First scan for available stationsradio02Stations = radio02.scan("Dallas")
print("Available stations in Dallas")print(radio02Stations)
print("Program the buttons")radio02.setStationNumber(1,radio02Stations[91.7])radio02.setStationNumber(2,radio02Stations[97.9])radio02.setStationNumber(3,radio02Stations[98.3])print("Play the three programmed stations")
radio02.playStation(3)radio02.playStation(2)
radio02.playStation(1) |
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