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While running program through the terminal we can stop the program by pressing 'Ctrl+c' and it will show the message as 'KeyboardInterrupt' . So, is there any way to do the sane thing by clicking the push-button in PyQt.

lkkkk
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    Why would you want to raise a `KeyboardInterrupt` error when _clicking_ a button? Or do you mean you just want to quit the program: i.e. `button.clicked.connect(QtGui.qApp.quit)`? – ekhumoro Apr 12 '14 at 13:22
  • But thing is that, I am doing program for ADC and ones the ADC starts reading under the 'while True:' loop then I am not able to stop it. And alternate option is giving interrupt of keyboard. Is there any way to stop the program as my program is running as root. – lkkkk Apr 12 '14 at 16:12
  • Always include information like that in your question, as it makes it _much_ easier to understand. Anyway, I have given an answer below which should solve your issue. – ekhumoro Apr 12 '14 at 17:02

2 Answers2

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If your program is running a loop, you can call processEvents periodically to allow the gui time to update (which should allow you to click a button to close the application):

    count = 0
    while True:
         count += 1
         if not count % 50:
             QtGui.qApp.processEvents()
         # do stuff...
ekhumoro
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  • I have posted another question related to above please suggest. Question link is : http://stackoverflow.com/questions/23057031/how-to-quit-the-program-in-while-loop-using-push-button-in-pyqt. I posted this after applying your above given answer but it didn't work,I don't know what is wrong. – lkkkk Apr 14 '14 at 09:58
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In my script to interrupt an infinite loop I also used QtGui.qApp.processEvents() and it worked out fine. The infinite loop writes to and reads data from a serial port and the user can interrupt the loop with a push button (1.condition).

def Move_Right(self):

    # move the slide right
    cmdPack = struct.pack(cmdStruct, Address, Rotate_Right, 0, Motor5, Speed5)
    dataByte = bytearray(cmdPack)
    checksumInt = sum(dataByte[:]) % 256
    msgPack = struct.pack(msgStruct, Address, Rotate_Right, 0, Motor5, Speed5, checksumInt)
    ser0.flushOutput() # Clear output buffer
    ser0.write(msgPack)

    # read the switch status
    cmdPack = struct.pack(cmdStruct, Address, Command.GAP, 10, Motor5, 0)
    dataByte = bytearray(cmdPack)
    checksumInt = sum(dataByte[:]) % 256
    msgPack = struct.pack(msgStruct, Address, Command.GAP, 10, Motor5, 0, checksumInt)
    ser0.flushOutput() # Clear output buffer

    # check the switch status with an infinite write/read loop with two break out conditions
    while True: 
        QtGui.qApp.processEvents()  # 1. condition: interrupt with push button
        ser0.write(msgPack)
        reply = ser0.read(9)
        answer = struct.unpack('>BBBBlB', reply)
        value = answer[4]
        command = answer[3]
        if (command == 6) and (value == 1):     # 2. condition: interrupt with limit switch
            print 'end of line'
            Stop_Motor5()
            break
parovelb
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