Which of the following commands can be used to read the entire contents of a file as a string using the file object Python?
In Python, the IO module provides methods of three types of IO operations; raw binary files, buffered binary files, and text files. The canonical way to create a file object is by using the open() function. Show
Any file operations can be performed in the following three steps:
Reading FileFile object includes the following methods to read data from the file.
The following C:\myfile.txt file will be used in all the examples of reading and writing files. This is the first line. This is the second line. This is the third line. The following example performs the read operation using the read(chars) method. >>> f = open('C:\myfile.txt') # opening a file >>> lines = f.read() # reading a file >>> lines 'This is the first line. \nThis is the second line.\nThis is the third line.' >>> f.close() # closing file object Above, f = open('C:\myfile.txt') opens the myfile.txt in the default read mode from the current directory and returns a file object. f.read() function reads all the content until EOF as a string. If you specify the char size argument in the read(chars) method, then it will read that many chars only. f.close() will flush and close the stream. Reading a LineThe following example demonstrates reading a line from the file. >>> f = open('C:\myfile.txt') # opening a file >>> line1 = f.readline() # reading a line >>> line1 'This is the first line. \n' >>> line2 = f.readline() # reading a line >>> line2 'This is the second line.\n' >>> line3 = f.readline() # reading a line >>> line3 'This is the third line.' >>> line4 = f.readline() # reading a line >>> line4 '' >>> f.close() # closing file object As you can see, we have to open the file in 'r' mode. The readline() method will return the first line, and then will point to the second line in the file. Reading All LinesThe following reads all lines using the readlines() function. >>> f = open('C:\myfile.txt') # opening a file >>> lines = f.readlines() # reading all lines >>> lines 'This is the first line. \nThis is the second line.\nThis is the third line.' >>> f.close() # closing file object The file object has an inbuilt iterator. The following program reads the given file line by line until StopIteration is raised, i.e., the EOF is reached. f=open('C:\myfile.txt') while True: try: line=next(f) print(line) except StopIteration: break f.close() Use the for loop to read a file easily. f=open('C:\myfile.txt') for line in f: print(line) f.close() This is the first line. This is the second line. This is the third line. Reading Binary FileUse the 'rb' mode in the open() function to read a binary files, as shown below. >>> f = open('C:\myimg.png', 'rb') # opening a binary file >>> content = f.read() # reading all lines >>> content b'\x89PNG\r\n\x1a\n\x00\x00\x00\rIHDR\x00\x00\x00\x08\x00\x00\x00\x08\x08\x06 \x00\x00\x00\xc4\x0f\xbe\x8b\x00\x00\x00\x19tEXtSoftware\x00Adobe ImageReadyq \xc9e\x00\x00\x00\x8dIDATx\xdab\xfc\xff\xff?\x03\x0c0/zP\n\xa4b\x818\xeco\x9c \xc2\r\x90\x18\x13\x03*8\t\xc4b\xbc\x01\xa8X\x07$\xc0\xc8\xb4\xf0>\\\x11P\xd7? \xa0\x84\r\x90\xb9\t\x88?\x00q H\xc1C\x16\xc9\x94_\xcc\x025\xfd2\x88\xb1\x04 \x88\x85\x90\x14\xfc\x05\xe2( \x16\x00\xe2\xc3\x8c\xc8\x8e\x84:\xb4\x04H5\x03 \xf1\\ .bD\xf3E\x01\x90\xea\x07\xe2\xd9\xaeB`\x82' >>> f.close() # closing file object Writing to a FileThe file object provides the following methods to write to a file.
Create a new File and WriteThe following creates a new file if it does not exist or overwrites to an existing file. >>> f = open('C:\myfile.txt','w') >>> f.write("Hello") # writing to file 5 >>> f.close() # reading file >>> f = open('C:\myfile.txt','r') >>> f.read() 'Hello' >>> f.close() In the above example, the f=open("myfile.txt","w") statement opens myfile.txt in write mode, the open() method returns the file object and assigns it to a variable f. 'w' specifies that the file should be writable. Next, f.write("Hello") overwrites an existing content of the myfile.txt file. It returns the number of characters written to a file, which is 5 in the above example. In the end, f.close() closes the file object. Appending to an Existing FileThe following appends the content at the end of the existing file by passing 'a' or 'a+' mode in the open() method. >>> f = open('C:\myfile.txt','a') >>> f.write(" World!") 7 >>> f.close() # reading file >>> f = open('C:\myfile.txt','r') >>> f.read() 'Hello World!' >>> f.close() Write Multiple LinesPython provides the writelines() method to save the contents of a list object in a file. Since the newline character is not automatically written to the file, it must be provided as a part of the string. >>> lines=["Hello world.\n", "Welcome to TutorialsTeacher.\n"] >>> f=open("D:\myfile.txt", "w") >>> f.writelines(lines) >>> f.close() Opening a file with "w" mode or "a" mode can only be written into and cannot be read from. Similarly "r" mode allows reading only and not writing. In order to perform simultaneous read/append operations, use "a+" mode. Writing to a Binary FileThe open() function opens a file in text format by default. To open a file in binary format, add 'b' to the mode parameter. Hence the "rb" mode opens the file in binary format for reading, while the "wb" mode opens the file in binary format for writing. Unlike text files, binary files are not human-readable. When opened using any text editor, the data is unrecognizable. The following code stores a list of numbers in a binary file. The list is first converted in a byte array before writing. The built-in function bytearray() returns a byte representation of the object. f=open("binfile.bin","wb") num=[5, 10, 15, 20, 25] arr=bytearray(num) f.write(arr) f.close() Which of the following commands is used to read the entire contents of a file as a string using the file object?fgets()– This function is used to read strings from files.
Which of the following commands can be used to read the entire contents of a file as a string using the file object fob?Explanation: read function is used to read all the lines in a file. 7.
Which of the following commands can be used to read the contents of a file in the form of list?The ls command is used to list files or directories in Linux and other Unix-based operating systems. Just like you navigate in your File explorer or Finder with a GUI, the ls command allows you to list all files or directories in the current directory by default, and further interact with them via the command line.
What is the command used to read a file in Python?Use the open() function with the 'r' mode to open a text file for reading. Use the read() , readline() , or readlines() method to read a text file. Always close a file after completing reading it using the close() method or the with statement.
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