Fix type errors

301.4 Data Types and Casting

Data Types and Casting — Note 4 of 4

Correct invalid type usage.

What you need to know

A TypeError happens when you use an operator on incompatible types, such as adding a string and an integer. The fix is to cast one value to match the other.

What to know

"5" + 3 causes TypeError — can't add str and int
Fix: int("5") + 3 or "5" + str(3)
input() always returns str — cast before maths
Read the error message to find the mismatched types

Code examples

Fixing a type error

python

age = input("Age: ")  # returns "15" (str)
# age + 1  ← TypeError!
age = int(age)
print(age + 1)  # 16

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Specification notes for programming are in Paper 2.