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📜  在Python中查看所有定义的变量

📅  最后修改于: 2022-05-13 01:54:51.919000             🧑  作者: Mango

在Python中查看所有定义的变量

在本文中，我们将讨论如何在Python中查看所有定义的变量。查看所有定义的变量在调试代码时起着重要作用。

方法一：使用dir()函数

dir()是一个内置函数，用于存储程序中的所有变量以及内置变量函数和方法。它创建一个包含所有声明和内置变量的列表。有两种不同的方法可以使用 dir( ) 查看所有定义的变量。它们将在下面讨论。

当没有用户定义的变量以 '__' 开头时：

  • 定义一些不以'__'开头的各种类型的变量
  • 调用 dir 并将其存储在变量中。它将之前定义的所有变量名以列表的形式存储，并将变量名存储为字符串。
  • 遍历存储 dir( ) 的整个列表。
  • 如果项目不以“__”开头，则打印该项目

例子：

Python3
# Define some variables of various types
# that are not starting with '__'
var2 = "Welcome to geeksforgeeks"
var3 = {"1": "a", "2": "b"}
var4 = 25
var5 = [1, 2, 3, 4, 5]
var6 = (58, 59)
  
# call dir and store it in a variable.
# It stores all the variable names defined
# before in the form of a list
# and stores the variable names as a string.
all_variables = dir()
  
# Iterate over the whole list where dir( )
# is stored.
for name in all_variables:
    
    # Print the item if it doesn't start with '__'
    if not name.startswith('__'):
        myvalue = eval(name)
        print(name, "is", type(myvalue), "and is equal to ", myvalue)

Python3
# Create a new variable and store all
# built-in functions within it using dir( ).
not_my_data = set(dir())
  
# Define some variables of various types.
var2 = "Welcome to geeksforgeeks"
var3 = {"1": "a", "2": "b"}
var4 = 25
var5 = [1, 2, 3, 4, 5]
var6 = (58, 59)
  
# Again call dir and store it in a list 
# subtracting the built-in variables stored
# previously.
my_data = set(dir()) - not_my_data
  
# Iterate over the whole list is stored.
for name in my_data:
    
    # Exclude the un-necessary variable named not_my_data
    if name != "not_my_data":
        val = eval(name)
        print(name, "is", type(val), "and is equal to ", val)

Python3
# Create a list of all global variables using
# globals( ) function, To store the built-in
# global variables.
not_my_data = set(globals())
  
# Declare some global variables
foo5 = "hii"
foo6 = 7
  
# Declare a function.
def func():
    
    # Declare some local variables inside it.
    var2 = "Welcome to geeksforgeeks"
    var3 = {"1": "a", "2": "b"}
    var4 = 25
    var5 = [1, 2, 3, 4, 5]
    var6 = (58, 59)
  
    # Store all the local variables in a list,
    # using locals keyword.
    locals_stored = set(locals())
      
    # Iterate over the list and print the local
    # variables.
    print("Printing Local Variables")
    for name in locals_stored:
        val = eval(name)
        print(name, "is", type(val), "and is equal to ", val)
  
    # Store the global variables in a list using 
    # globals keyword and subtract the previously
    # created list of built-in global variables from it.
    globals_stored = set(globals())-not_my_data
      
    # Print the global variables
    print("\nPrinting Global Variables")
    for name in globals_stored:
        
        # Excluding func and not_my_data as they are 
        # also considered as a global variable
        if name != "not_my_data" and name != "func":
            val = eval(name)
            print(name, "is", type(val), "and is equal to ", val)
  
  
# Call the function.
func()

输出：

存储内置变量并忽略它们

  • 创建一个新变量并使用 dir( ) 在其中存储所有内置函数。
  • 定义一些不同类型的变量。
  • 再次调用 dir 并将其存储在减去先前存储的内置变量的列表中。
  • 遍历整个列表。
  • 打印所需的项目

例子：

蟒蛇3 

# Create a new variable and store all
# built-in functions within it using dir( ).
not_my_data = set(dir())
  
# Define some variables of various types.
var2 = "Welcome to geeksforgeeks"
var3 = {"1": "a", "2": "b"}
var4 = 25
var5 = [1, 2, 3, 4, 5]
var6 = (58, 59)
  
# Again call dir and store it in a list 
# subtracting the built-in variables stored
# previously.
my_data = set(dir()) - not_my_data
  
# Iterate over the whole list is stored.
for name in my_data:
    
    # Exclude the un-necessary variable named not_my_data
    if name != "not_my_data":
        val = eval(name)
        print(name, "is", type(val), "and is equal to ", val)

输出：

方法二：打印局部变量和全局变量

Locals() 是一个内置函数，它返回该特定范围内所有局部变量的列表。 globals() 对全局变量也做同样的事情。

方法

  • 使用 globals()函数创建所有全局变量的列表，以存储内置全局变量。
  • 声明一些全局变量
  • 声明一个函数。
  • 在里面声明一些局部变量。
  • 使用 locals 关键字将所有局部变量存储在一个列表中。
  • 遍历列表并打印局部变量。
  • 使用 globals 关键字将全局变量存储在列表中，并从中减去先前创建的内置全局变量列表。
  • 打印它们。
  • 调用函数。

例子：

蟒蛇3 

# Create a list of all global variables using
# globals( ) function, To store the built-in
# global variables.
not_my_data = set(globals())
  
# Declare some global variables
foo5 = "hii"
foo6 = 7
  
# Declare a function.
def func():
    
    # Declare some local variables inside it.
    var2 = "Welcome to geeksforgeeks"
    var3 = {"1": "a", "2": "b"}
    var4 = 25
    var5 = [1, 2, 3, 4, 5]
    var6 = (58, 59)
  
    # Store all the local variables in a list,
    # using locals keyword.
    locals_stored = set(locals())
      
    # Iterate over the list and print the local
    # variables.
    print("Printing Local Variables")
    for name in locals_stored:
        val = eval(name)
        print(name, "is", type(val), "and is equal to ", val)
  
    # Store the global variables in a list using 
    # globals keyword and subtract the previously
    # created list of built-in global variables from it.
    globals_stored = set(globals())-not_my_data
      
    # Print the global variables
    print("\nPrinting Global Variables")
    for name in globals_stored:
        
        # Excluding func and not_my_data as they are 
        # also considered as a global variable
        if name != "not_my_data" and name != "func":
            val = eval(name)
            print(name, "is", type(val), "and is equal to ", val)
  
  
# Call the function.
func()

输出：