Programming Articles - Page 593 of 3363

The r in r-strings means raw strings. String literals may optionally be prefixed with a letter 'r' or 'R'; such strings are called raw strings and use different rules for interpreting backslash escape sequences. When an 'r' or 'R' prefix is present, a character following a backslash is included in the string without change, and all backslashes are left in the string. For example, the string literal r"" consists of two characters − a backslash and a lowercase 'n'. String quotes can be escaped with a backslash, but the backslash remains in the string; for example, r""" is ... Read More

Yes, there is no goto statement in Python. Let us first understand what is a goto in C Language. However, the usage of goto is also discouraged in C. The goto statement in C programming provides an unconditional jump from the 'goto' to a labelled statement in the same function. Following is the syntax − goto label; .. . label: statement; Example Let us now see a C program for goto − #include int main () { int a = 10; LOOP:do { if( a == 15) { /* skip the iteration */ a = a + 1; goto LOOP; } printf("a = %d", a); a++; }while( a

Let us first see what is an interface spec. The interface spec is an interface specification for a module provided by programming languages such as C++ and Java. It describes the prototypes for the methods and functions of the module. The abc module The abc module introduced in Python 2.6 to define Abstract Base Classes (ABCs). Use the isinstance() and issubclass() to check whether an instance or a class implements a particular Abstract Base Class. With that, the collections.abc module defines a set of useful ABCs such as Iterable, Container, and MutableMapping. The collections module has classes that derive from ... Read More

Example In this example, let’s first see the usage of list.sort() before moving further. Here, we have created a List and sorted in Ascending order using the sort() method − # Creating a List myList = ["Jacob", "Harry", "Mark", "Anthony"] # Displaying the List print("List = ", myList) # Sort the Lists in Ascending Order myList.sort() # Display the sorted List print("Sort (Ascending Order) = ", myList) Output List = ['Jacob', 'Harry', 'Mark', 'Anthony'] Sort (Ascending Order) = ['Anthony', 'Harry', 'Jacob', 'Mark'] Where performance matters more, making a copy of the list just ... Read More

In Python to display calendar, you need to import calendar module, it provides various functions to handle operations related to calendar, and also includes printing a text calendar for a month . Calendar Module The calendar module in python provides various functions and classes to perform date-related operations. To print a calendar in Python, we import the calendar module, which will import all module classes. Key Features Some of the features provided by Calendar module are as follows: Calendar Functions: To generate HTML or text format ... Read More

Regular expressions, often known as RegEx, are a string of characters corresponding to letters, words, or character patterns in text strings. It implies that you may use regular expressions to match and retrieve any string pattern from the text. Search and replace procedures benefit from the usage of regular expressions. The most common application is searching for a substring that matches a pattern and substituting something else. What are whitespace characters? "Whitespace" refers to any letter or set of characters representing either horizontal or vertical space. Using regular expressions, the metacharacter “\s” matches whitespace characters in python. Algorithm ... Read More

Introduction The re-module is what we use in Python for regular expressions. Text searches and more complex text manipulation employ regular expressions. Tools like grep and sed, text editors like vi and emacs, and computer languages like Tcl, Perl, and Python all have built-in regular expression support. The re-module in Python offers functions for matching regular expressions. A regular expression that defines the text we are looking for or modifying is called a pattern. Text literals and metacharacters make up this string. The compile function is used to create the pattern. Raw strings are advised since regular expressions ... Read More

To understand why dictionary keys must be immutable. Let us related it to hash table. The hash table implementation of dictionaries uses a hash value calculated from the key value to find the key. If let’s say the key was a mutable object, its value could change, and thus its hash could also change. As stated above, since whoever changes the key object can’t tell that it was being used as a dictionary key, it can’t move the entry around in the dictionary. Then, When you try to look up the same object in the dictionary it won’t be ... Read More

CPython is the default and most widely used interpreter or implementation of Python. It is the original Python version and understands the code written using python specifications. Python is quite serious about cleaning up memory on exit and does try to destroy every single object, but unfortunately objects referenced from the global namespaces of Python modules are not always deallocated when Python exits. The reason are circular references. There are also certain bits of memory that are allocated by the C library that are impossible to free. Use the atexit module to force Python to delete certain things on deallocation. ... Read More

Yes, Python Lambda Expressions cannot contain statements. Before deep diving the reason, let us understand what is a Lambda, its expressions, and statements. The Lambda expressions allow defining anonymous functions. A lambda function is an anonymous function i.e. a function without a name. Let us see the syntax − lambda arguments: expressions The keyword lambda defines a lambda function. A lambda expression contains one or more arguments, but it can have only one expression. Lambda Example Let us see an example − myStr = "Thisisit!" (lambda myStr : print(myStr))(myStr) Output Thisisit! Sort a List by values from ... Read More