What are the data type conversion functions in Python?

Python is a powerful programming language that provides a wealth of data type conversion functions to facilitate conversion between different data types. This article will introduce commonly used data type conversion functions in Python and provide corresponding code examples.

1. int() function:
   int() function is used to convert a number or string into an integer. It can handle signed numeric strings as well as floating point numbers. If the conversion to an integer cannot be performed, a ValueError exception is raised.

Sample code:

num_str = "123"
num = int(num_str)
print(num, type(num))  # 输出：123 <class 'int'>

pi_str = "3.14159"
pi = int(float(pi_str))
print(pi, type(pi))  # 输出：3 <class 'int'>

invalid_str = "abc"
try:
    invalid_num = int(invalid_str)
except ValueError as e:
    print(f"无法将字符串 {invalid_str} 转换为整数")  # 输出：无法将字符串 abc 转换为整数

2. float() function:
   float() function is used to convert a number or string to a floating point number. It can handle numeric strings with positive and negative signs, as well as strings represented in scientific notation. If the conversion to a floating point number cannot be performed, a ValueError exception is raised.

Sample code:

num_str = "3.14"
num = float(num_str)
print(num, type(num))  # 输出：3.14 <class 'float'>

invalid_str = "abc"
try:
    invalid_num = float(invalid_str)
except ValueError as e:
    print(f"无法将字符串 {invalid_str} 转换为浮点数")  # 输出：无法将字符串 abc 转换为浮点数

3. str() function:
   str() function is used to convert other data types to strings. It can handle integers, floating point numbers, Boolean values ​​and other types. It can also convert complex data structures such as lists, tuples, and dictionaries into strings.

Sample code:

num = 123
num_str = str(num)
print(num_str, type(num_str))  # 输出：123 <class 'str'>

pi = 3.14159
pi_str = str(pi)
print(pi_str, type(pi_str))  # 输出：3.14159 <class 'str'>

my_list = [1, 2, 3]
list_str = str(my_list)
print(list_str, type(list_str))  # 输出：[1, 2, 3] <class 'str'>

4. bool() function:
   bool() function is used to convert other data types to Boolean values. In general, non-zero values ​​in numeric types are converted to True, and zero values ​​are converted to False; non-empty strings in string types are converted to True, and empty strings are converted to False; empty lists, tuples, dictionaries, etc. is False.

Sample code:

num = 123
num_bool = bool(num)
print(num_bool, type(num_bool))  # 输出：True <class 'bool'>

zero = 0
zero_bool = bool(zero)
print(zero_bool, type(zero_bool))  # 输出：False <class 'bool'>

my_str = "abc"
str_bool = bool(my_str)
print(str_bool, type(str_bool))  # 输出：True <class 'bool'>

empty_str = ""
empty_str_bool = bool(empty_str)
print(empty_str_bool, type(empty_str_bool))  # 输出：False <class 'bool'>

empty_list = []
empty_list_bool = bool(empty_list)
print(empty_list_bool, type(empty_list_bool))  # 输出：False <class 'bool'>

The above is an introduction to commonly used data type conversion functions in Python, including int(), float(), str() and bool() functions. Through these functions, we can flexibly convert between different data types. In actual programming, we can choose appropriate conversion functions to operate data as needed.

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