How to use str in Python?

2 years ago
Isabella Edwards
2 minutes

In Python, str is a built-in data type that is used for creating and manipulating strings.

To create a string:
You can use either single or double quotation marks to create a string, as shown below:

str1 = 'Hello'
str2 = "World"

Strings can contain any characters, including letters, numbers, special characters, etc.

Operations on Strings:
In Python, strings are immutable, meaning once a string is created, its value cannot be changed. However, new strings can be created through various operations.

  1. String concatenation:
    You can use the plus operator (+) to concatenate strings, as shown below:
str3 = str1 + str2
print(str3)  # 输出：HelloWorld
  1. String indexing and slicing:
    You can use indexing to access individual characters in a string, where the index starts at 0, as shown below:
print(str1[0])  # 输出：H

You can use slicing to obtain a part of a string. The syntax for slicing is [start:end:step], where start is the starting index, end is the ending index (not inclusive), and step is the increment. By default, step is set to 1. For example:

print(str1[1:4])  # 输出：ell
  1. Length of string:
    You can use the len function to obtain the length of a string, as shown below:
print(len(str1))  # 输出：5
  1. String formatting:
    You can format a string using the format method, as shown below:
name = 'Alice'
age = 25
print("My name is {}, and I am {} years old.".format(name, age))
# 输出：My name is Alice, and I am 25 years old.
  1. Other common actions:
  1. Check whether a string contains a certain substring by using the ‘in’ keyword, like ‘l’ in str1.
  2. Changing the case of a string: use the upper method to convert the string to uppercase, and use the lower method to convert the string to lowercase.
  3. To remove spaces from both ends of a string, use the strip method.
  4. Find the position of a substring in a string: use either the find method or the index method.
  5. Replace a substring: Use the replace method.

This is only a part of string manipulation, there are many other methods and functions available for handling strings.

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