Python open()函数

Python open()函数用于 open() 内部存储的文件。它将文件的内容作为Python对象返回。

Syntax: open(file_name, mode) 

Parameters:

file_name: This parameter as the name suggests, is the name of the file that we want to open.

mode: This parameter is a string that is used to specify the mode in which the file is to be opened. The following strings can be used to activate a specific mode:

• “r”: This string is used to read(only) the file. It is passed as default if no parameter is supplied and returns an error if no such file exists.
• “w”: This string is used for writing on/over the file. If the file with the supplied name doesn’t exist, it creates one for you.
• “a”: This string is used to add(append) content to an existing file. If no such file exists, it creates one for you.
• “x”: This string is used to create a specific file.
• “b”: This string is used when the user wants to handle the file in binary mode. This is generally used to handle image files.
• “t”: This string is used to handle files in text mode. By default, the open() function uses the text mode.

示例 1：创建文本文件

以下代码可用于创建文件。在这里，我们将创建一个名为“geeksforgeeks.txt”的文本文件。

Python3

created_file = open("geeksforgeeks.txt","x")
  
# Check the file
print(open("geeksforgeeks.txt","r").read() == False)

输出：

True

示例 2：读取和写入文件

在这里，我们将以下字符串写入我们刚刚创建的geeksforgeeks.txt文件并再次读取同一个文件。

Geeksforgeeks is best for DSA

下面的代码可用于相同的：

蟒蛇3

my_file = open("geeksforgeeks.txt", "w")
my_file.write("Geeksforgeeks is best for DSA")
my_file.close()
  
#let's read the contents of the file now
my_file = open("geeksforgeeks.txt","r")
print(my_file.read())

输出：

Geeksforgeeks is best for DSA

示例 3：将内容附加到文件

在这里，我们将以下文本附加到 geeksforgeeks.txt 文件并再次读取相同内容：

蟒蛇3

my_file = open("geeksforgeeks.txt","a")
my_file.write("..>>Visit geeksforgeeks.org for more!!<<..")
my_file.close()
  
# reading the file
my_file = open("geeksforgeeks.txt","r")
print(my_file.read())

输出：

Geeksforgeeks is best for DSA..>>Visit geeksforgeeks.org for more!!<<..

注意： “w”和“r”之间的区别在于，一个覆盖现有内容，而后者将内容添加到现有文件中，保持内容不变。