Python gui

源代码：
from tkinter import *
a = Tk()
a.title('林计算')
a.geometry('260x455')

def numberinput(number):
first_num=en.get()
en.delete(0,END)
print(number,type(number))
en.insert(0,str(first_num)+str(number))

def clear():
en.delete(0,END)
an.delete(0,END)

def plus():
global o
global first_mum
global second_mum
first_mum=en.get()
en.delete(0,END)
o='add'

def minus():
global o
global first_mum
first_mum=en.get()

en.delete(0,END)
o='min'

def multi():
global o
global first_mum
first_mum=en.get()

en.delete(0,END)
o='mul'

def times():
global o
global first_mum
first_mum=en.get()
en.delete(0,END)
o='div'

def equal():
second_mum=en.get()
en.delete(0,END)

if o=='add':
    en.insert(0,first_mum+'+'+second_mum)
    an.insert(0,int(first_mum)+int(second_mum))
if o=='min':
    en.insert(0,first_mum+'-'+second_mum)
    an.insert(0,int(first_mum)-int(second_mum))
if o=='mul':
    en.insert(0,first_mum+'*'+second_mum)
    an.insert(0,int(first_mum)*int(second_mum))
if o=='div':
    en.insert(0,first_mum+'/'+second_mum)
    an.insert(0,int(first_mum)/int(second_mum))

bu1=Button(a,text=1,width=2,font=('Arial',31),command=lambda:numberinput(1))
bu2=Button(a,text=2,width=2,font=('Arial',31),command=lambda:numberinput(2))
bu3=Button(a,text=3,width=2,font=('Arial',31),command=lambda:numberinput(3))
bu4=Button(a,text=4,width=2,font=('Arial',31),command=lambda:numberinput(4))
bu5=Button(a,text=5,width=2,font=('Arial',31),command=lambda:numberinput(5))
bu6=Button(a,text=6,width=2,font=('Arial',31),command=lambda:numberinput(6))
bu7=Button(a,text=7,width=2,font=('Arial',31),command=lambda:numberinput(7))
bu8=Button(a,text=8,width=2,font=('Arial',31),command=lambda:numberinput(8))
bu9=Button(a,text=9,width=2,font=('Arial',31),command=lambda:numberinput(9))
bu0=Button(a,text=0,width=2,font=('Arial',31),command=lambda:numberinput(0))
bu_eq=Button(a,text='=',width=2,font=('Arial',31),command=lambda:equal())
bu_clear=Button(a,text='C',width=2,font=('Arial',31),command=lambda:clear())
bu_add=Button(a,text='+',width=2,font=('Arial',31),command=lambda:plus())
bu_min=Button(a,text='-',width=2,font=('Arial',31),command=lambda:minus())
bu_mul=Button(a,text='*',width=2,font=('Arial',31),command=lambda:multi())
bu_div=Button(a,text='/',width=2,font=('Arial',31),command=lambda:times())
bu1.place(x=15,y=100)
bu2.place(x=75,y=100)
bu3.place(x=135,y=100)
bu4.place(x=15,y=185)
bu5.place(x=75,y=185)
bu6.place(x=135,y=185)
bu7.place(x=15,y=270)
bu8.place(x=75,y=270)
bu9.place(x=135,y=270)
bu0.place(x=75,y=355)
bu_eq.place(x=135,y=355)
bu_clear.place(x=15,y=355)
bu_add.place(x=195,y=100)
bu_min.place(x=195,y=185)
bu_mul.place(x=195,y=270)
bu_div.place(x=195,y=355)

an=Entry(a,width=10,font=('Arial',31))
an.place(x=10,y=45)
en=Entry(a,width=10,font=('Arial',31))
en.place(x=10,y=00)

a.mainloop()

写代码的感受：当要布局的窗口比较多的时候，用place不尽代码很长，不易书写，而且定位的像素坐标试了好久，非常麻烦，如果选用pack或grid来布局，会简单很多。我写的思路比较简单，但书写操作起来麻烦；如果用grid来写，可能思路上困难一些，但是敲代码的过程肯定会简单很多。在网上看见了篇代码：
from tkinter import *
reset=True
def buttonCallBack(event):
global label
global reset
num=event.widget['text']
if num'C':
label['text']="0"
return
if num in "=":
label['text']=str(eval(label['text']))
reset=True
return
s=label['text']
if s'0' or reset==True:
s=""
reset=False
label['text']=s+num

主窗口

root=Tk()
root.wm_title("林计算")

显示栏1

label=Label(root,text="0",background="yellow",anchor="e")
label['width']=55
label['height']=6
label.grid(row=1,columnspan=4,sticky=W)

按钮

showText="789/456123-0.C+"
for i in range(4):
for j in range(4):
b=Button(root,text=showText[i4+j],width=7)
b.grid(row=i+2,column=j)
b.bind("",buttonCallBack)
showText="()"
for i in range(2):
b=Button(root,text=showText[i],width=7)
b.grid(row=6,column=2+i)
b.bind("",buttonCallBack)
b=Button(root,text="=")
b.grid(row=6,columnspan=2,sticky="we")
b.bind("",buttonCallBack)
root.mainloop()

书写简单，而且功能也比我强大。感觉自己写代码的路还有很多长要走。
附件1：我的代码执行
附件2：网络上代码执行
参考：https://www.cnblogs.com/pinpin/p/10052193.html