Impara Creating and Inspecting Strings

Strings are how Python stores text - names, messages, file paths, even emoji. In Python 3, strings are Unicode by default, so they can represent characters from virtually any language.

What Is a String?

A string is an immutable sequence of characters. "Immutable" means you don't change a string in place; instead, operations create a new string.


              123
            
title = "Python 101"
emoji = "🙂"
print(title, emoji)

Creating Strings

Python lets you write string literals with single or double quotes; choose whichever makes the code clearer.


              123456
            
a = "hello"
b = 'he said: "hi"'
c = "it's fine to mix quotes like this"
print(a)
print(b)
print(c)

If you need multiple lines, use triple-quoted strings. Python keeps the line breaks.


              123
            
message = """Line 1
Line 2"""
print(message)

To include special characters (like a newline) in a single line, use escape sequences.


              12
            
greet = "hello\nworld"   # \n is a single newline character
print(greet)

When backslashes should be taken literally (e.g., Windows paths or simple regex patterns), a raw string helps.


              12
            
path = r"C:\Users\alex\docs"   # backslashes are not treated as escapes
print(path)

Inspecting Strings (without indexing yet)

You'll often need quick checks: "what is this?" and "how long is it?"


              123
            
s = "hello"
print(type(s))     # <class 'str'>
print(len(s))      # 5

An empty string is considered falsey, while any non-empty string is truthy. That's handy in conditions.


              12345
            
name = ""
if name:
    print("Welcome,", name)
else:
    print("Please enter your name")  # runs because "" is falsey

Note

"" (empty) is not the same as " " (a space). len("") == 0, len(" ") == 1;
\n counts as one character (a newline), so len("A\nB") == 3;
Prefer raw strings for paths to avoid accidental escapes like "\t" (tab).

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Sezione 3. Capitolo 1

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Suggested prompts:

Can you explain more about string immutability?

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Strings are how Python stores text - names, messages, file paths, even emoji. In Python 3, strings are Unicode by default, so they can represent characters from virtually any language.

What Is a String?

A string is an immutable sequence of characters. "Immutable" means you don't change a string in place; instead, operations create a new string.


              123
            
title = "Python 101"
emoji = "🙂"
print(title, emoji)

Creating Strings

Python lets you write string literals with single or double quotes; choose whichever makes the code clearer.


              123456
            
a = "hello"
b = 'he said: "hi"'
c = "it's fine to mix quotes like this"
print(a)
print(b)
print(c)

If you need multiple lines, use triple-quoted strings. Python keeps the line breaks.


              123
            
message = """Line 1
Line 2"""
print(message)

To include special characters (like a newline) in a single line, use escape sequences.


              12
            
greet = "hello\nworld"   # \n is a single newline character
print(greet)

When backslashes should be taken literally (e.g., Windows paths or simple regex patterns), a raw string helps.


              12
            
path = r"C:\Users\alex\docs"   # backslashes are not treated as escapes
print(path)

Inspecting Strings (without indexing yet)

You'll often need quick checks: "what is this?" and "how long is it?"


              123
            
s = "hello"
print(type(s))     # <class 'str'>
print(len(s))      # 5

An empty string is considered falsey, while any non-empty string is truthy. That's handy in conditions.


              12345
            
name = ""
if name:
    print("Welcome,", name)
else:
    print("Please enter your name")  # runs because "" is falsey

Note

"" (empty) is not the same as " " (a space). len("") == 0, len(" ") == 1;
\n counts as one character (a newline), so len("A\nB") == 3;
Prefer raw strings for paths to avoid accidental escapes like "\t" (tab).

Tutto è chiaro?

Grazie per i tuoi commenti!

Sezione 3. Capitolo 1

Creating and Inspecting Strings

What Is a String?

Creating Strings

Inspecting Strings (without indexing yet)

1. Which is a valid string literal in Python?

2. What value will this code output?

3. Which statement is true?

Awesome!

Creating and Inspecting Strings

What Is a String?

Creating Strings

Inspecting Strings (without indexing yet)

1. Which is a valid string literal in Python?

2. What value will this code output?

3. Which statement is true?