python 3.6中的缩进错误

Question

When i run this code in IDLE, i get a SyntaError(expected an indent block) The thing is that i dont see any indentation problem. What the code does: It reads 'cities.txt' file(with string lines) It then copies those lines in 'out.txt', after enumeration in each line

try:
    with open('cities.txt', 'r+') as inp:
except FileNotFoundError:
    print('File not found')
except:
    print('Error')
else:
    try:
        with open('out.txt', 'a+') as out:
    except FileNotFoundError:
        print('File not found')
    except:
        print('Error')
    else:
        for i, line in enumerate(inp):
            out.write(str(i+1)+': '+line)
            print(str(i+1)+': '+line, end='\n')

Answer 1

with x as y:应该紧跟一个缩进的代码块，该代码块可以完成您想要使用的资源-基本上是您在else块中拥有的

Answer 2

To ensure logic and format, you should write your code like this :

try:
    with open('out.txt', 'a+') as out:
        for i, line in enumerate(inp):
            out.write(str(i+1)+': '+line)
            print(str(i+1)+': '+line, end='\n')
except FileNotFoundError:
    print('File not found')
except:
    print('Error')