python 过滤文件内容

Question

我是 python 新手，我正在尝试执行以下作业，但我的输出与预期的不同。任何人都可以帮我解决这里的问题吗？感谢您的帮助!

作业:

在第三个程序中，我们研究一下文件内容的分类。与源代码在同一目录中有一个文件“strings.txt”，其中有几行随机字符串。这些行可以分为两组:一组仅包含字母(a-z、A-Z)和数字(0-9)，一组还包含随机特殊字符(?、&、@、$ ...)。

创建一个程序，从文件中读取所有行并测试这些行。如果该行只有字母和/或数字，程序将打印“[line] was ok.”。如果该行有特殊字符，程序应该打印“[line] was invalid.”。当程序运行时，它会打印出如下内容:

5345m345ö34l was ok.
no2no123non4 was ok.
noq234n5ioqw#% was invalid.
%#""SGMSGSER was invalid.
doghdp5234 was ok.
sg,dermoepm was invalid.
43453-frgsd was invalid.
hsth())) was invalid.
bmepm35wae was ok.
vmopaem2234+0+ was invalid.
gsdm12313 was ok.
bbrbwb55be3"?"#? was invalid.
"?"#%#"!%#"&"?%%"?#?#"?" was invalid.
retrte#%#?% was invalid.
abcdefghijklmnopqrstuvxy was ok.

建议一次读取一行，使用 isalmun() 字符串测试对其进行测试，然后从那里继续。另请记住，字符串也可以以换行符 (\n) 结尾，这是允许的，但如果不将其切掉，则无法通过 .isalnum() 测试。 示例输出

5345m34534l was invalid.
no2no123non4 was ok.
noq234n5ioqw#% was invalid.
%#""SGMSGSER was invalid.
doghdp5234 was ok.
sg,dermoepm was invalid.
43453-frgsd was invalid.
hsth())) was invalid.
bmepm35wae was ok.
vmopaem2234+0+ was invalid.
gsdm12313 was ok.
gswrgsrdgrsgsig45 was ok.
)/(/)(#=%#)%/ was invalid.
++-+-+--+--+-+>-<+-<<_<-+>>++ was invalid.

我的代码是

handle = open("strings.txt","r")
content = handle.read()
content.isalnum()
for i in content:
    if content.isalnum()==True:
        print(content,"was ok")
    else:
        print(content,"was invalid")

handle.close()

我的输出是

5345m34534l
no2no123non4
noq234n5ioqw#%
%#""SGMSGSER
doghdp5234
sg,dermoepm
43453-frgsd
hsth()))
bmepm35wae
vmopaem2234+0+
gsdm12313
gswrgsrdgrsgsig45
)/(/)(#=%#)%/
++-+-+--+--+-+>-<+-<<_<-+>>++. was invalid
5345m34534l
no2no123non4
noq234n5ioqw#%
%#""SGMSGSER
doghdp5234
sg,dermoepm
43453-frgsd
hsth()))
bmepm35wae
vmopaem2234+0+
gsdm12313
gswrgsrdgrsgsig45
)/(/)(#=%#)%/
++-+-+--+--+-+>-<+-<<_<-+>>++. was invalid
5345m34534l
no2no123non4
noq234n5ioqw#%
%#""SGMSGSER
doghdp5234
sg,dermoepm
43453-frgsd
hsth()))
bmepm35wae
vmopaem2234+0+
gsdm12313
gswrgsrdgrsgsig45
)/(/)(#=%#)%/
++-+-+--+--+-+>-<+-<<_<-+>>++. was invalid

# etc ad nauseum...

我做错了什么？

Answer 1

handle = open("strings.txt","r")
content = handle.read()  # <= here you read in the entire file
content.isalnum()
for i in content:      # <= here you iterate over each **character** of the file
    if content.isalnum()==True:
        print(content,"was ok")
               # ^ here you print the entire input file each time
    else:
        print(content,"was invalid")
               # ^ (ditto) which is why you have so much output
handle.close()

相反，尝试

with open("strings.txt") as inf:
    for line in inf:
        line = line.rstrip()
        if line.isalnum():
            print("{} was ok".format(line))
        else:
            print("{} was invalid".format(line))