12. String Operations

• The basic operations are slicing, concatenation, and formatting.

• Slicing allows you to use part of a string

• Concatenation, in contrast, is used to join two or more strings

• Finally, formatting is used heavily when sending messages to the console and consists of using strings as templates where we can insert data

12.1. Concatenation

1 a = "Potato" 2 b = "when born" 3 print(a + b) 4 print(a * 3) Edit this code line that just executed next line to execute << First < Prev Next > Last >> Step 1 of 4 Submit Python Tutor by Philip Guo Customize visualization (NEW!)

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12.2. Slicing

• We can perform the slicing operation using [start_index:end_index]

1 x = "0123456789" 2 print(x[0:2]) 3 print(x[1:2]) 4 print(x[2:4]) 5 print(x[0:5]) 6 print(x[1:8]) Edit this code line that just executed next line to execute << First < Prev Next > Last >> Step 1 of 6 Submit Python Tutor by Philip Guo Customize visualization (NEW!)

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• We can omit indices, replacing the corresponding index, and we can also have negative indices: -1 last, -2 penultimate

1 x = "0123456789" 2 print(x[:2]) 3 print(x[4:]) 4 print(x[4:-1]) 5 print(x[-4:-1]) 6 print(x[:]) Edit this code line that just executed next line to execute << First < Prev Next > Last >> Step 1 of 6 Submit Python Tutor by Philip Guo Customize visualization (NEW!)

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12.3. Formatting

• Joining multiple strings is not always practical

• We can use placeholders to replace values within strings

1 age = 20 2 print("Juan is %d years old" % age) Edit this code line that just executed next line to execute << First < Prev Next > Last >> Step 1 of 2 Submit Python Tutor by Philip Guo Customize visualization (NEW!)

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• The main placeholders are %d for integers, %s for strings, and %f for floating-point numbers

• % 03d complete with additional zeros

• % 3d means three positions without additional zeros

1 age = 20 2 print("[%03d]" % age) 3 print("[%3d]" % age) Edit this code line that just executed next line to execute << First < Prev Next > Last >> Step 1 of 3 Submit Python Tutor by Philip Guo Customize visualization (NEW!)

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• %5.2f means 5 characters in total and 2 decimals

1 print("$%5.2f pesos" % 23) Edit this code line that just executed next line to execute << First < Prev Next > Last >> Step 1 of 1 Submit Python Tutor by Philip Guo Customize visualization (NEW!)

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12.4. f-strings

• Another way to join strings is through f-strings

• Everything inside braces {} will be replaced if previously defined. In the example, .2f means two decimal places.

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1

price = 10.123

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print(f"The price is: ${price:.2f}")

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