#
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# calculate project                                                           #
#author: josh                                                                 #
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from __future__ import division
import sys
from math import *
from PyQt4.QtCore import *
from PyQt4.QtGui import *

class Form(QDialog):
    super(Form, self).__init__(parent)
    self.browser = QTextBrowser()
    self.lineedit =  QLineEdit("Type an expression and press Enter")
    self.lineedit = selectAll()
    layout = QVBoxLayout()
    layout.addWidget(self.browser)
    layout.addWidget(self.lineedit)
    self.setLayout(layout)
    self.lineedit.setFocus()
    self.connect(self.lineedit, SIGNAL("returnPressed()"),
        self.updateUi)
    self.setWindowTitle("Calculate")
def updateUi(self):
    try:
        text = unicode(self.lineedit.text())
        self.borwser.append("%s = <b>%s</b>" % (text, eval(text)))
    except:
        self.browser.append(
            "<font color=red>%s is invalid!</font>" % text)
app = QAppliction(sys.argv)
form = Form()
form.show()
app.exec_()