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Python | Output using print() function

  • Difficulty Level : Easy
  • Last Updated : 16 Jul, 2021

The simplest way to produce output is using the print() function where you can pass zero or more expressions separated by commas. This function converts the expressions you pass into a string before writing to the screen. 

Syntax: print(value(s), sep= ‘ ‘, end = ‘\n’, file=file, flush=flush)
Parameters: 
value(s) : Any value, and as many as you like. Will be converted to string before printed 
sep=’separator’ : (Optional) Specify how to separate the objects, if there is more than one.Default :’ ‘ 
end=’end’: (Optional) Specify what to print at the end.Default : ‘\n’ 
file : (Optional) An object with a write method. Default :sys.stdout 
flush : (Optional) A Boolean, specifying if the output is flushed (True) or buffered (False). Default: False
Returns: It returns output to the screen.

Though it is not necessary to pass arguments in the print() function, it requires an empty parenthesis at the end that tells python to execute the function rather calling it by name. Now, let’s explore the optional arguments that can be used with the print() function.

1. String Literals

String literals in python’s print statement are primarily used to format or design how a specific string appears when printed using the print() function.

  • \n : This string literal is used to add a new blank line while printing a statement.
  • “” : An empty quote (“”) is used to print an empty line.

Example:



Python3




print ("GeeksforGeeks \n is best for DSA Content.")

Output:

GeeksforGeeks 
 is best for DSA Content.

2. end= ” ” statement

The end keyword is used to specify the content that is to be printed at the end of the execution of the print() function. By default, it is set to “\n”, which leads to the change of line after the execution of print() statement.

Example:

Python3




# This line will automatically add a new line before the
# next print statement
print ("GeeksForGeeks is the best platform for DSA content")
 
# This print() function ends with "**" as set in the end argument.
print ("GeeksForGeeks is the best platform for DSA content", end= "**")

Output:

GeeksForGeeks is the best platform for DSA content
GeeksForGeeks is the best platform for DSA content**

3. flush Argument

The I/Os in python is generally buffered, meaning they are used in chunks. This is where flush comes in as it helps users to decide if they need the written content to be buffered or not. By default, it is set to false. If it is set to true, the output will be written as a sequence of characters one after the other. This process is slow simply because it is easier to write in chunks rather than writing one character at a time. To understand the use case of the flush argument in the print() function, let’s take an example.

Example:

Imagine you are building a countdown timer, which appends the remaining time to the same line every second. It would look something like below:

3>>>2>>>1>>>Start

The initial code for this would look something like below;



Python3




import time
 
count_seconds = 3
for i in reversed(range(count_seconds + 1)):
    if i > 0:
        print(i, end='>>>')
        time.sleep(1)
    else:
        print('Start')

So, the above code adds text without a trailing newline and then sleeps for one second after each text addition. At the end of the countdown, it prints Start and terminates the line. If you run the code as it is, it waits for 3 seconds and abruptly prints the entire text at once. This is a waste of 3 seconds caused due to buffering of the text chunk as shown below:

Though buffering serves a purpose, it can result in undesired effects as shown above. To counter the same issue, the flush argument is used with the print() function. Now, set the flush argument as true and again see the results.

Python3




import time
 
count_seconds = 3
for i in reversed(range(count_seconds + 1)):
    if i > 0:
        print(i, end='>>>', flush = True)
        time.sleep(1)
    else:
        print('Start')

Output:

4. Separator

The print() function can accept any number of positional arguments. These arguments can be separated from each other using a “,” separator. These are primarily used for formatting multiple statements in a single print() function.

Example:

Python3




b = "for"
 
print("Geeks", b , "Geeks")

Output:

Geeks for Geeks

5. file Argument

Contrary to popular belief, the print() function doesn’t convert the messages into text on the screen. These are done by lower-level layers of code, that can read data(message) in bytes. The print() function is an interface over these layers, that delegates the actual printing to a stream or file-like object. By default, the print() function is bound to sys.stdout through the file argument. 

Example:

Python3




import io
 
# declare a dummy file
dummy_file = io.StringIO()
 
# add message to the dummy file
print('Hello Geeks!!', file=dummy_file)
 
# get the value from dummy file
dummy_file.getvalue()

Output:

'Hello Geeks!!\n'

Example : Using print() function in Python
 

Python3




# Python 3.x program showing
# how to print data on
# a screen
 
# One object is passed
print("GeeksForGeeks")
 
x = 5
# Two objects are passed
print("x =", x)
 
# code for disabling the softspace feature
print('G', 'F', 'G', sep ='')
 
# using end argument
print("Python", end = '@'
print("GeeksforGeeks")
Output
GeeksForGeeks
x = 5
GFG
Python@GeeksforGeeks

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