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Articles by Pythonista
18 articles
Why we can't use arrow operator in gets and puts?
You can't read user input in an un-initialized pointer. Instead, have a variable of the struct data type and assign its address to pointer before accessing its inner elements by → operatorexample#include struct example{ char name[20]; }; main(){ struct example *ptr; struct example e; puts("enter name"); gets(e.name); ptr=&e; puts(ptr->name); }OutputTypical result of above codeenter name Disha You entered Disha
Read MorePython - How to convert this while loop to for loop?
Usin count() function in itertools module gives an iterator of evenly spaced values. The function takes two parameters. start is by default 0 and step is by default 1. Using defaults will generate infinite iterator. Use break to terminate loop.import itertools percentNumbers = [ ] finish = "n" num = "0" for x in itertools.count() : num = input("enter the mark : ") num = float(num) percentNumbers.append(num) finish = input("stop? (y/n) ") if finish=='y':break print(percentNumbers)Sample output of the above scriptenter the mark : 11 stop? (y/n) enter the mark : 22 stop? (y/n) enter the mark : 33 stop? (y/n) y [11.0, 22.0, 33.0]
Read MoreHow to emulate a do-while loop in Python?
Python doesn't have an equivalent of do-while loop as in C/C++ or Java. The essence of do-while loop is that the looping condition is verified at the end of looping body. This feature can be emulated by following Python code −Examplecondition=True x=0 while condition==True: x=x+1 print (x) if x>=5: condition=FalseOutputThe output is as follows −1 2 3 4 5
Read MoreWhat is vertical bar in Python bitwise assignment operator?
Vertical bar (|) stands for bitwise or operator. In case of two integer objects, it returns bitwise OR operation of two>>> a=4 >>> bin(a) '0b100' >>> b=5 >>> bin(b) '0b101' >>> a|b 5 >>> c=a|b >>> bin(c) '0b101'
Read MoreHow to implement Python __lt__ __gt__ custom (overloaded) operators?
Python has magic methods to define overloaded behaviour of operators. The comparison operators (=, == and !=) can be overloaded by providing definition to __lt__, __le__, __gt__, __ge__, __eq__ and __ne__ magic methods. Following program overloads < and > operators to compare objects of distance class. class distance: def __init__(self, x=5,y=5): self.ft=x self.inch=y def __eq__(self, other): if self.ft==other.ft and self.inch==other.inch: return "both objects are equal" else: return "both objects are not equal" def __lt__(self, other): in1=self.ft*12+self.inch in2=other.ft*12+other.inch if in1
Read MoreHow to overload Python comparison operators?
Python has magic methods to define overloaded behaviour of operators. The comparison operators (=, == and !=) can be overloaded by providing definition to __lt__, __le__, __gt__, __ge__, __eq__ and __ne__ magic methods. Following program overloads == and >= operators to compare objects of distance class.class distance: def __init__(self, x=5, y=5): self.ft=x self.inch=y def __eq__(self, other): if self.ft==other.ft and self.inch==other.inch: return "both objects are equal" ...
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 do we convert a string to a set in Python?
Python’s standard library contains built-in function set() which converts an iterable to set. A set object doesn’t contain repeated items. So, if a string contains any character more than once, that character appears only once in the set object. Again, the characters may not appear in the same sequence as in the string as set() function has its own hashing mechanism>>> set("hello") {'l', 'h', 'o', 'e'}
Read MoreHow to insert a Python tuple in a PostgreSql database?
PostgreSql database is by default installed on port number 5432. Python interface to PostgreSql is provided by installing psycopg2 module. Assuming that test database and employee table with fname, sname, age, gender and salary fields is available.First establish connection and obtain cursor object by following statements in Python script.import psycopg2 conn = psycopg2.connect(database = "test", user = "postgres", password = "pass123", host = "localhost", port = "5432") cur = conn.cursor()Data to be inserted in employee table is stored in the form of tuple objectt1=('Mac', 'Mohan', 20, 'M', 2000)Next set up the insert query using this tuplesql="insert into employee values(%s, %s, ...
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