关于Python文件写入的问题

[zhangwhhx]

import os
ls1=[['10001','苹果'],['10002','香蕉'],['10003','桔子']]
file_name = "test.txt"
while True:
    bianhao=input("请输入编号(输入-1退出):")
    for ls in ls1:
        if bianhao==ls[0]:
            shuliang = int(input("请输入数量:"))
            try:
                with open(file_name,"a") as file:
                    lsjs = [ls[0], ls[1], str(shuliang)]
                    file.write(",".join(lsjs) + "\n")
                break
            except IOError:
                with open(file_name, "w") as fo:
                    ls2 = ["商品编号", "商品名称", "数量"]
                    fo.write(",".join(ls2)+"\n")
                    lsjs=[ls[0],ls[1],str(shuliang)]
                    fo.write(",".join(lsjs)+"\n")
                break
        elif bianhao == "-1":
            os._exit(0)
        else:
            print('编号不存在')
以上代码，当不存在test.txt时，为什么不能写入两行，只能写入1行呢

[CSDN-Ada助手]

您可以前往 CSDN问答-Python 发布问题, 以便更快地解决您的疑问