Casting

301.4 Data Types and Casting

Data Types and Casting — Note 3 of 4

Convert between strings & numbers.

What you need to know

Casting converts a value from one type to another. Use int(), float(), and str() to convert. This is essential when working with input(), which always returns a string.

What to know

int("5") converts string to integer → 5
float("3.14") converts string to float → 3.14
str(42) converts integer to string → "42"
int(3.9) truncates to 3 (does not round)

Code examples

Casting examples

python

num_str = "42"
num = int(num_str)     # 42 as int
pi = float("3.14")    # 3.14 as float
label = str(100)       # "100" as string

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Specification notes for programming are in Paper 2.