为何从tkinter文本框获取字符串时搜索功能失效？

从Tkinter文本框提取字符串执行搜索时功能失效，但直接将关键词定义为字符串常量时搜索正常。最小复现代码如下：

import tkinter as tk
root = tk.Tk()
string="banana\napplepie\napple\n"

def searchcall():
 
    textboxcontent=textExample.get("1.0","end")
    keyword=filterbox.get("1.0","end")
    keyword="apple" # 取消注释这行搜索正常

    print("keyword",keyword)
    print("is keyword in textbox",keyword in textboxcontent)
    for elem in textboxcontent.split():
        print("seaching for",keyword,"in",elem,keyword in elem)
 
        

textExample=tk.Text(root, height=10)
textExample.insert(1.0,string)
textExample.pack()
filterbox=tk.Text(root, height=1)
filterbox.insert(1.0,"apple")
filterbox.pack()
btnRead=tk.Button(root, height=1, width=11, text="search", 
                    command=searchcall)

btnRead.pack()
root.mainloop()

Tkinter的Text组件使用get("1.0", "end")获取内容时，会自动在返回的字符串末尾添加一个换行符\n。比如你在filterbox中输入"apple"，实际拿到的关键词是"apple\n"，和手动定义的"apple"不匹配，导致搜索失效。

获取文本内容时，将"end"替换为"end-1c"，end-1c表示末尾位置往前偏移1个字符，这样就能去掉多余的换行符：

def searchcall():
    # 用end-1c替代end，去除末尾多余换行
    textboxcontent=textExample.get("1.0","end-1c")
    keyword=filterbox.get("1.0","end-1c")
    # keyword="apple" # 现在可以注释掉这行，搜索正常运行

    print("keyword",keyword)
    print("is keyword in textbox",keyword in textboxcontent)
    for elem in textboxcontent.split():
        print("seaching for",keyword,"in",elem,keyword in elem)

内容的提问来源于stack exchange，提问作者Nivatius