在我的计算器中，如何让它只求解一次方程式，并在清除计算器后阻止用户输入？

问题描述

我正在使用tkinter创建一个计算器，并且很难弄清楚如何只能使计算器解决用户一次输入的问题，并防止进一步输入到下一行（我的输出文本小部件只有两行）。我尝试将输入仅插入第一行，但只会继续在第一行插入更多输入。甚至有可能只是阻止按钮在按下'='之后直到我按下清除按钮时根本不能插入任何东西吗？

#function handles all calculations and inputs
def calc(data):
    #gets last character in output
    last_value = output.get('end -2 chars')

    #condition how data should be inserted
    if data.isnumeric() or data == '.': 
        output.insert('end',data)
        if last_value == '.' and data == '.': #prevents duplicating decimals
            output.replace('end -3 chars','end -1 chars',data)
    elif data in "+-*/":
        output.insert('end',data)
        if last_value in "+-/*": #prevents duplicating operators also replaces existing operators
            output.replace('end-3c','end-1c',data)
    elif data == 'C':
        output.delete('1.0','end')

    #solves equation
    elif data == '=':
        equation = output.get('end -1 lines linestart','end -1 lines lineend')
        try:
            answer = eval(equation)
            output.insert('end','\n' + str(answer))
        except SyntaxError:
            output.insert('end','\n' + 'ERROR: SYNTAX')
        except ZeroDivisionError:
            output.insert('end','\n' + 'ERROR: 0 DIVISION')

解决方法

由于任何原因，您不能只存储一个变量，该变量指定是否允许计算。并在第一次计算后更新并清除？

def calc(data):
    #gets last character in output
    last_value = output.get('end -2 chars')

    #condition how data should be inserted
    if data.isnumeric() or data == '.' and can_calculate: #make sure we're allowed to calculate/update
        output.insert('end',data)
        if last_value == '.' and data == '.': #prevents duplicating decimals
            output.replace('end -3 chars','end -1 chars',data)
    elif data in "+-*/" and can_calculate: #make sure we're allowed to calculate/update
        output.insert('end',data)
        if last_value in "+-/*": #prevents duplicating operators also replaces existing operators
            output.replace('end-3c','end-1c',data)
    elif data == 'C':
        output.delete('1.0','end')
        can_calculate=True #update var to reflect a calculation because we cleared

    #solves equation
    elif data == '=' and can_calculate:
        equation = output.get('end -1 lines linestart','end -1 lines lineend')
        try:
            answer = eval(equation)
            output.insert('end','\n' + str(answer))
            can_calculate = False #update var to reflect a calculation because we calculated
        except SyntaxError:
            output.insert('end','\n' + 'ERROR: SYNTAX')
        except ZeroDivisionError:
            output.insert('end','\n' + 'ERROR: 0 DIVISION')