在这种情况下我应该如何插入 try-except

Question

Task1

Write a script that reads a string from STDIN and raise ValueError exception if the string has more than 10 characters or else prints the read string.

I wrote the code like this

a = input("Enter a string")
if(len(a) > 10):
    raise ValueError
else:
    print(a)

Task2

Use try... except clauses. Print the error message inside except block.

I am now confused about how to use try-except here because to print any message in except block the program has to fail at try block.

My input will be PythonIsAmazing

Answer 1

You can just wrap the whole thing in try... except as follows:

a = input("Enter a string: ")

try:
    if(len(a) > 10):
        raise ValueError
    print(a)
except ValueError:
    print("String was longer than 10 characters")

Alternatively, if you had lots of different ValueErrors that might be raised, you could give each a separate error message:

a = input("Enter a string: ")

try:
    if(len(a) > 10):
        raise ValueError("String was longer than 10 characters")
    print(a)
except ValueError as e:
    print(e)

Eg:

Enter a string: test
test

Enter a string: PythonIsAmazing
String was longer than 10 characters