String validation checks in Python - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does the str.isalpha() method check in a string?

It checks if all characters in the string are letters (a-z or A-Z) and the string is not empty.

intermediate

How does str.isdigit() differ from str.isnumeric()?

str.isdigit() checks if all characters are digits (0-9), while str.isnumeric() also returns True for numeric characters like fractions or superscripts.

beginner

What does str.isspace() check for in a string?

It returns True if the string contains only whitespace characters like spaces, tabs, or newlines, and is not empty.

beginner

Explain the use of str.isalnum().

It checks if all characters in the string are letters or numbers (no spaces or symbols) and the string is not empty.

beginner

What will 'Hello123'.isalpha() return and why?

It will return False because the string contains numbers along with letters, and isalpha() requires only letters.

Which method checks if a string contains only letters and is not empty?

A isalpha()

B isdigit()

C isspace()

D isalnum()

isalpha() returns True only if all characters are letters and the string is not empty.

What does str.isdigit() return for the string '12345'?

A True

B False

C Error

D Depends on Python version

Since '12345' contains only digits, isdigit() returns True.

Which method would return True for a string containing only spaces and tabs?

A isalnum()

B isnumeric()

C isalpha()

D isspace()

isspace() returns True if the string contains only whitespace characters.

What will 'abc123'.isalnum() return?

A Error

B True

C False

D None

isalnum() returns True if all characters are letters or numbers, which is true here.

Which method is best to check if a string contains only numeric characters including fractions or superscripts?

A isalpha()

B isdigit()

C isnumeric()

D isspace()

isnumeric() covers a wider range of numeric characters than isdigit().

Describe how you can check if a string contains only letters or numbers in Python.

Think about a method that allows both letters and digits but no spaces.

Explain the difference between isdigit() and isnumeric() methods.

Consider what kinds of numeric characters each method accepts.