Turn Text into a Whole Number

The previous lesson introduced a pattern you can now reuse:

function(argument) -> return value

int() is another function. It accepts a value as an argument and returns a new integer.

book_count = int(book_count_text)

In this call:

• int is the function.

• book_count_text is the argument.

• The converted integer is the return value.

• The assignment stores that return value in book_count.

The arrow above is explanatory notation, not Python syntax.

Turn typed text into a whole number

When an answer represents a whole number, use int() to convert the string into an integer.

book_count_text = input("How many books? ")
book_count = int(book_count_text)

The first line collects text. The second line calls int() with that text and stores the returned integer.

If the person enters 12, the values are:

The quotation marks in the table help show the difference. They are not part of what the person typed.

Conversion produces a new value

int(book_count_text) does not change the original string. It produces a new integer value, which this program assigns to book_count.

Now arithmetic works:

after_one_more = book_count + 1

If book_count is 12, after_one_more becomes 13.

Here is the complete book-count example:

book_count_text = input("How many books? ")
book_count = int(book_count_text)
after_one_more = book_count + 1
print(f"With one more, you would have {after_one_more} books.")

Notice the three distinct values: the original string, the converted integer, and the result of the calculation.

A shorter form

You may also see the function calls nested:

book_count = int(input("How many books? "))

Python works from the inside out. input() returns a string, then int() receives that string as its argument and returns an integer.

Both forms work. Separate lines are often easier to inspect while you are learning or debugging.

number_text = "7"
number = int(number_text)
print(number + 2)

Finish the age program

The starter program collects an age as text. Two placeholder values still prevent it from calculating the following year’s age.

Replace those placeholders so the program:

1. converts the value in age_text to an integer named age;

2. calculates next_age by adding 1 to age.

Keep the final f-string. If the person enters 40, the final line should be:

Next year you will be 41.

Do not copy the book variable names into the exercise. Apply the same function pattern to the age variables already present in the starter code.

During Run, use a whole number. During Submit, Python Land supplies its own whole-number answer.