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Python Articles
Page 811 of 852
How to read all HTTP headers in Python CGI script?
It is possible to get a custom request header's value in an apache CGI script with python. The solution is similar to this.Apache's mod_cgi will set environment variables for each HTTP request header received, the variables set in this manner will all have an HTTP_ prefix, so for example x-client-version: 1.2.3 will be available as variable HTTP_X_CLIENT_VERSION.So, to read the above custom header just call os.environ["HTTP_X_CLIENT_VERSION"].The below script will print all HTTP_* headers and values −#!/usr/bin/env python import os print "Content-Type: text/html" print "Cache-Control: no-cache" print print "" for headername, headervalue in os.environ.iteritems(): if headername.startswith("HTTP_"): print "{0} = {1}".format(headername, headervalue) ...
Read MoreHow to use else conditional statement with for loop in python?
The else block in a loop (for as well as while) executes after all iterations of loop are completed and before the program flow exits the loop body. The syntax is as follows −Syntaxwhile expr==True: #statements to be iterated while expr is true. else: #this statement(s) will be executed afteriterations are over#this will be executed after the program leaves loop bodyexamplefor x in range(6): print (x) else: print ("else block of loop") print ("loop is over")OutputThe output is as shown below −0 1 2 3 4 5 else block of loop loop is over
Read MoreHow to generate prime numbers using Python?
A prime number is the one that is not divisible by any other number except 1 and itself.In Python % modulo operator is available to test if a number is divisible by other. Assuming we have to find prime numbers between 1 to 100, each number (let us say x) in the range needs to be successively checked for divisibility by 2 to x-1. This is achieved by employing two nested loops.for x in range(1,101): for y in range(2,x): if x%y==0:break else: print (x,sep=' ', end=' ')Above code generates prime numbers between 1-1001 2 3 5 7 11 13 17 19 23 29 31 37 41 43 47 53 59 61 67 71 73 79 83 89 97
Read MoreHow to print a value for a given key for Python dictionary?
Python dictionary is collection of key value pairs. Value associated with a certain key is returned by get() method.>>> D1={'a':11,'b':22,'c':33} >>> D1.get('b') 22You can also obtain value by using key inside square brackets.>>> D1['c'] 33
Read MoreHow to indent multiple if...else statements in Python?
Use of indented blocks is an important feature of Python. Indent level of the block is more than previous statements. Hence, if multiple if statements are present in a program in nested fashion, each subsequent indented block will have increasing level of indent.if expr1==True: if expr2==True: stmt1 else: if expr3==True: stmt2 else: if expr3==True: stmt3 else: stmt4
Read MoreCan we use break statement in a Python if clause?
Python's break keyword is used as decision control statement. It causes the remaining iterations to be abandoned and control of execution goes to next statement after the end of loop. Invariably it is executed conditionally and appears inside if block within a loop.while expr==True: stmt1 stmt2 if expr2==True: break stmt3 stmt4 However it can't be used in an if block if it is not a part of loop.
Read MoreCan we use continue statement in a Python if clause?
Python's continue statement is a loop control statement. It causes starting next iteration of loop after abandoning current iteration. Invariably is is executed conditionally i.e. in if blockwhile expr==True: stmt1 stmt2 if expr2==True: continue stmt3 stmt4However, it can't be used in an if block if it is not a part of loop. If used, interpreter will throw syntax error.
Read MoreWhat are the >> and << operators in Python?
The symbols > are defined as left and right shift operators respectively in Python. They are bitwise operators. First operand is a bitwise representation of numeric object and second is the number of positions by which bit formation is desired to be shifted to left or right.The >> a=60 >>> bin(a) '0b111100' >>> b=a> b 240 >>> bin(b) '0b11110000'You can see two bits on right set to 0On the other hand >> operator shifts pattern to right. Most significant bits are set to 0>>> a=60 >>> bin(a) '0b111100' >>> b=a>>2 >>> b 15 >>> bin(a) '0b111100'
Read MoreHow does == operator works in Python 3?
The == symbol is defined as equality operator. It returns true if expressions on either side are equal and false if they are not equal>>> (10+2) == 12 True >>> 5*5 == 5**2 True >>> (10/3)==3 False >>> 'computer'=="computer" True >>> 'COMPUTER'.lower()=='computer' True
Read MoreWhat does 'is not' operator do in Python?
In Python, is and is not operators are called identity operators. Each object in computer's memory is assigned a unique identification number (id) by Python interpreter. Identity operators check if id() of two objects is same. 'is not' operator returns true of id() values are different and false if they are same.>>> a=10 >>> b=a >>> id(a), id(b) (490067904, 490067904) >>> a is not b False >>> a=10 >>> b=20 >>> id(a), id(b) (490067904, 490068064) >>> a is not b True
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