Understanding Python String Prefixes: u, r, b, and f

In Python, string prefixes are used to denote special string types, and this article explains the four common prefixes and their meanings.

u prefix (Unicode) : Indicates a Unicode string. In Python 3 all strings are Unicode by default, so the u prefix is rarely needed. Example: u"Hello World" .

r prefix (Raw) : Creates a raw string where backslashes are treated literally and escape sequences are not processed. Example: r"C:\Users\Username" .

b prefix (Bytes) : Denotes a bytes literal, used for binary data. Bytes strings are sequences of bytes and can contain any binary data. Example: b"Hello World" .

f prefix (Formatted) : Introduces an f‑string, allowing expressions and variables to be embedded directly within the string using curly braces. Example: name = "Alice"; f"Hello, {name}!" .

These prefixes are optional, but selecting the appropriate one can make string handling clearer and more convenient.

# Unicode字符串
name = u"李雷"
print(name)  # 输出：李雷
# 原始字符串
path = r"C:\Users\Username"
print(path)  # 输出：C:\Users\Username
# 字节字符串
data = b"\x48\x65\x6c\x6c\x6f"  # ASCII编码的"Hello"
print(data)  # 输出：b"Hello"
# 格式化字符串
age = 25
print(f"My age is {age}." )  # 输出：My age is 25.

The examples demonstrate how each prefix affects string interpretation: Unicode strings for text, raw strings to ignore escapes, bytes strings for binary data, and formatted strings for convenient interpolation.