用python操作文本文件

Question

我有一个打开文件input.txt的任务，它包含两行:

100-50
50-25

然后我需要执行减法(计算给定的表达式)并将它们写在output.txt中。输出应该如下所示:

100-50=50
50-25=25

到目前为止，我有这个:

with open('input.txt','r') as file1:
x=file1.read()
print(x)

但是我不知道如何继续计算给定的输入。

Answer 1

with open('input.txt','r') as f1:
lines = f1.readlines()
with open('output.txt', 'w') as f2:
for line in lines:
sub = int(line.split("-")[0]) - int(line.split("-")[1])
f2.write(line.replace("n", "") + "=" + str(sub) + "n")