Watch Now This tutorial has a related video course created by the Real Python team. Watch it together with the written tutorial to deepen your understanding: Comparing Python Objects the Right Way: “is” vs “==” There’s a subtle difference between the Python identity operator ( is ) and the equality operator ( == ).
- Your code can run fine when you use the Python is operator to compare numbers, until it suddenly doesn’t,
- You might have heard somewhere that the Python is operator is faster than the == operator, or you may feel that it looks more Pythonic,
- However, it’s crucial to keep in mind that these operators don’t behave quite the same.
The == operator compares the value or equality of two objects, whereas the Python is operator checks whether two variables point to the same object in memory. In the vast majority of cases, this means you should use the equality operators == and !=, except when you’re comparing to None,
What the difference is between object equality and identity When to use equality and identity operators to compare objects What these Python operators do under the hood Why using is and is not to compare values leads to unexpected behavior How to write a custom _eq_() class method to define equality operator behavior
Python Pit Stop: This tutorial is a quick and practical way to find the info you need, so you’ll be back to your project in no time! Free Bonus: Click here to get a Python Cheat Sheet and learn the basics of Python 3, like working with data types, dictionaries, lists, and Python functions.
Contents
- 1 What is double == in Python?
- 2 What does == 0 mean in Python?
- 3 What does using the if __ name __ == ‘__ main __’ syntax allow programmers to do?
- 4 What does I 3 == 0 mean in Python?
- 5 What is the difference between __ init __ and __ main __?
- 6 What does double () do?
What is double == in Python?
What is the difference between Python’s equality operators?
Python, Type, Comparison · Jun 12, 2021 
Python provides two very similar equality operators used for comparisons:
- The double equals ( == ), also known as the equality operator
- The is keyword, also known as the identity operator
Although similar to one another, the double equals ( == ) and the is keyword are used for different comparison purposes and yield different results. The main difference between the two is that the is keyword checks for reference equality while the double equals ( == ) operator checks for value equality.
In other words, is will return True if two variables both refer to the same object in memory (aka. identity), whereas the double equals operator will evaluate to True if the two objects have the same value. Here are some examples to clear up any confusion: a = b = a c = print ( ) x = ‘hi’ y = x z = ‘HI’,
lower ( ) print ( )
What is %% in Python?
%% means a percent symbol after using the % operator on your string. % is a special symbol for substitutions, so when you put ‘Hi %s’%name. you are substituting a variable into the string at the point where %s occurs.
What does == VS mean in Python?
Python ‘is’ vs ‘==’ Operator: Head-to-Head Comparison –
| Parameters | is | == |
| What it compares | Checks if two objects are same or not | Checks it the value of two objects is same or not |
| Comparison | Compares variables and strings | Compares only variables |
| Type of Operator | Identity operator | Equality operator |
What is == 1 in Python?
You’re testing if a string is equal to an integer, which it never can be. Python doesn’t convert the values on both sides of == to the same type.1 == 1 would return True and ‘1’ == ‘1’ would return True, but the string, ‘1’, is not equal to the integer, 1.
What does == 0 mean in Python?
== 0 means ‘ equal to 0 (zero) ‘. So if foo == 0: means ‘do the following if foo is equal to 0’, thus if x % 2 == 0: means ‘do the following if x % 2 is equal to 0’. Follow this answer to receive notifications.
What does using the if __ name __ == ‘__ main __’ syntax allow programmers to do?
In Short: It Allows You to Execute Code When the File Runs as a Script, but Not When It’s Imported as a Module – For most practical purposes, you can think of the conditional block that you open with if _name_ == “_main_” as a way to store code that should only run when your file is executed as a script. You’ll see what that means in a moment. For now, say you have the following file: 1 # echo.py 2 3 def echo ( text : str, repetitions : int = 3 ) -> str : 4 “””Imitate a real-world echo.””” 5 echoed_text = “” 6 for i in range ( repetitions, 0, – 1 ): 7 echoed_text += f ” \n ” 8 return f “,” 9 10 if _name_ == “_main_” : 11 text = input ( “Yell something at a mountain: ” ) 12 print ( echo ( text )) In this example, you define a function, echo(), that mimics a real-world echo by gradually printing fewer and fewer of the final letters of the input text. Below that, in lines 10 to 12, you use the if _name_ == “_main_” idiom. This code starts with the conditional statement if _name_ == “_main_” in line 10. In the indented lines, 11 and 12, you then collect user input and call echo() with that input. These two lines will execute when you run echo.py as a script from your command line: $ python echo.py Yell something at a mountain: HELLOOOO ECHOOOOOOOOOO ooo oo o, When you run the file as a script by passing the file object to your Python interpreter, the expression _name_ == “_main_” returns True, The code block under if then runs, so Python collects user input and calls echo(), Try it out yourself! You can download all the code files that you’ll use in this tutorial from the link below: At the same time, if you import echo() in another module or a console session, then the nested code won’t run: >>> >>> from echo import echo >>> print ( echo ( “Please help me I’m stuck on a mountain” )) ain in n, In this case, you want to use echo() in the context of another script or interpreter session, so you won’t need to collect user input. Running input() would mess with your code by producing a side effect when importing echo, When you nest the code that’s specific to the script usage of your file under the if _name_ == “_main_” idiom, then you avoid running code that’s irrelevant for imported modules. Nesting code under if _name_ == “_main_” allows you to cater to different use cases:
Script: When run as a script, your code prompts the user for input, calls echo(), and prints the result. Module: When you import echo as a module, then echo() gets defined, but no code executes. You provide echo() to the main code session without any side effects.
By implementing the if _name_ == “_main_” idiom in your code, you set up an additional entry point that allows you to use echo() right from the command line. There you go! You’ve now covered the most important information about this topic. Still, there’s more to find out, and there are some subtleties that can help you build a deeper understanding of this code specifically and Python more generally.
Is ++ allowed in Python?
Is there a ++ operator in Python? No, there is no ++ operator in Python. This was a clear design decision by the developers of the Python language.
What is %s and %d in Python?
In Python both %s and %d are placeholders for a string and a number respectively. name = ‘Robey’ number = 454 print ‘%s %d’ % (name, number) %s will return the string and %d will return number, the values are passed using % operator. This % operator formatting is used in C language also.
How to use += in Python?
Newline character in Python: – In Python, the new line character “\n” is used to create a new line. When inserted in a string all the characters after the character are added to a new line. Essentially the occurrence of the “\n” indicates that the line ends here and the remaining characters would be displayed in a new line.
What is Python 2 vs 3 ?
Python 3 has an easier syntax compared to Python 2. A lot of libraries of Python 2 are not forward compatible. A lot of libraries are created in Python 3 to be strictly used with Python 3. Python 2 is no longer in use since 2020.
Can we use
Less Than or Equal To ( We will quickly learn how to write less than or equal to in Python. The less than or equal to operator, denoted by returns True only if the value on the left is either less than or equal to that on the right of the operator.
Can you use == for strings in Python?
Conclusion – In this article you learned how to compare strings in Python using the equality ( == ) and comparison ( <, >, !=, <=, >= ) operators. Continue your learning about Python strings,
Is 0 false in Python?
4.10. Type conversion ¶ – Each Python type comes with a built-in command that attempts to convert values of another type into that type. The int(ARGUMENT) command, for example, takes any value and converts it to an integer, if possible, or complains otherwise: >>> int ( “32” ) 32 >>> int ( “Hello” ) ValueError: invalid literal for int() with base 10: ‘Hello’ int can also convert floating-point values to integers, but remember that it truncates the fractional part: >>> int ( – 2.3 ) -2 >>> int ( 3.99999 ) 3 >>> int ( “42” ) 42 >>> int ( 1.0 ) 1 The float(ARGUMENT) command converts integers and strings to floating-point numbers: >>> float ( 32 ) 32.0 >>> float ( “3.14159” ) 3.14159 >>> float ( 1 ) 1.0 It may seem odd that Python distinguishes the integer value 1 from the floating-point value 1.0, They may represent the same number, but they belong to different types. The reason is that they are represented differently inside the computer. The str(ARGUMENT) command converts any argument given to it to type string : >>> str ( 32 ) ’32’ >>> str ( 3.14149 ) ‘3.14149’ >>> str ( True ) ‘True’ >>> str ( true ) Traceback (most recent call last): File ” “, line 1, in NameError : name ‘true’ is not defined str(ARGUMENT) will work with any value and convert it into a string. As mentioned earlier, True is boolean value; true is not. For boolean values, the situation is especially interesting: >>> bool ( 1 ) True >>> bool ( 0 ) False >>> bool ( “Ni!” ) True >>> bool ( “” ) False >>> bool ( 3.14159 ) True >>> bool ( 0.0 ) False Python assigns boolean values to values of other types. For numerical types like integers and floating-points, zero values are false and non-zero values are true. For strings, empty strings are false and non-empty strings are true.
How to do ++ in Python?
In Python += is used for incrementing, and -= for decrementing. In some other languages, there is even a special syntax ++ and – for incrementing or decrementing by 1. Python does not have such a special syntax. To increment x by 1 you have to write x += 1 or x = x + 1.
Is it difficult to learn Python?
Why learn Python? – Python is widely considered among the easiest programming languages for beginners to learn. If you’re interested in learning a programming language, Python is a good place to start. It’s also one of the most widely used. The TIOBE Index for June 2021 lists Python as the second most popular language after C, and its popularity is growing,
What does %2 == 1 mean in Python?
Therefore the (if number%2 == 1) function tests to see if the number is odd. If it returns true then your program continues and print the number. If the number is not odd the program ends.
What does I 3 == 0 mean in Python?
It means that the remainder must be equal to zero when that number is divided by 3. == means ‘equal to’. Hope this helps.
What does %2 == 0 mean in Python?
Will someone explain this statement ” if number % 2 == 0:” number % 2 == 0 is a valid boolean expression that checks whether number % 2 is equivalent to 0, For even number s, the result is the value, True, But, number 2% == 0 is not a valid expression, because % == is not a valid operator. : Will someone explain this statement ” if number % 2 == 0:”
Why __ name __ == ‘__ main __’ is used in Python?
What does the if name main do in Python This article explains what the Python code expression if _name_ == ‘_main_’ means. A Python programme uses the condition if _name_ == ‘_main_’ to only run the code inside the if statement when the program is run directly by the Python interpreter. The code inside the if statement is not executed when the file’s code is imported as a module.
What is the difference between __ init __ and __ main __?
_init_.py, among other things, labels a directory as a python directory and lets you set variables on a package wide level. _main_.py, among other things, is run if you try to run a compressed group of python files. _main_.py allows you to execute packages.
What is __ name __ in Python?
What is the purpose of _name_ ? – Before executing a program, the Python interpreter assigns the name of the python module into a special variable called _name_, Depending on whether you are executing the program through command line or importing the module into another module, the assignment for _name_ will vary.
What does double () do?
DOUBLE –
What data type is a double?
The Java programming language is statically-typed, which means that all variables must first be declared before they can be used. This involves stating the variable’s type and name, as you’ve already seen: Doing so tells your program that a field named “gear” exists, holds numerical data, and has an initial value of “1”.
- A variable’s data type determines the values it may contain, plus the operations that may be performed on it.
- In addition to int, the Java programming language supports seven other primitive data types,
- A primitive type is predefined by the language and is named by a reserved keyword.
- Primitive values do not share state with other primitive values.
The eight primitive data types supported by the Java programming language are:
byte : The byte data type is an 8-bit signed two’s complement integer. It has a minimum value of -128 and a maximum value of 127 (inclusive). The byte data type can be useful for saving memory in large arrays, where the memory savings actually matters. They can also be used in place of int where their limits help to clarify your code; the fact that a variable’s range is limited can serve as a form of documentation. short : The short data type is a 16-bit signed two’s complement integer. It has a minimum value of -32,768 and a maximum value of 32,767 (inclusive). As with byte, the same guidelines apply: you can use a short to save memory in large arrays, in situations where the memory savings actually matters. int : By default, the int data type is a 32-bit signed two’s complement integer, which has a minimum value of -2 31 and a maximum value of 2 31 -1. In Java SE 8 and later, you can use the int data type to represent an unsigned 32-bit integer, which has a minimum value of 0 and a maximum value of 2 32 -1. Use the Integer class to use int data type as an unsigned integer. See the section The Number Classes for more information. Static methods like compareUnsigned, divideUnsigned etc have been added to the Integer class to support the arithmetic operations for unsigned integers. long : The long data type is a 64-bit two’s complement integer. The signed long has a minimum value of -2 63 and a maximum value of 2 63 -1. In Java SE 8 and later, you can use the long data type to represent an unsigned 64-bit long, which has a minimum value of 0 and a maximum value of 2 64 -1. Use this data type when you need a range of values wider than those provided by int, The Long class also contains methods like compareUnsigned, divideUnsigned etc to support arithmetic operations for unsigned long. float : The float data type is a single-precision 32-bit IEEE 754 floating point. Its range of values is beyond the scope of this discussion, but is specified in the Floating-Point Types, Formats, and Values section of the Java Language Specification. As with the recommendations for byte and short, use a float (instead of double ) if you need to save memory in large arrays of floating point numbers. This data type should never be used for precise values, such as currency. For that, you will need to use the java.math.BigDecimal class instead. Numbers and Strings covers BigDecimal and other useful classes provided by the Java platform. double : The double data type is a double-precision 64-bit IEEE 754 floating point. Its range of values is beyond the scope of this discussion, but is specified in the Floating-Point Types, Formats, and Values section of the Java Language Specification. For decimal values, this data type is generally the default choice. As mentioned above, this data type should never be used for precise values, such as currency. boolean : The boolean data type has only two possible values: true and false, Use this data type for simple flags that track true/false conditions. This data type represents one bit of information, but its “size” isn’t something that’s precisely defined. char : The char data type is a single 16-bit Unicode character. It has a minimum value of ‘\u0000’ (or 0) and a maximum value of ‘\uffff’ (or 65,535 inclusive).
In addition to the eight primitive data types listed above, the Java programming language also provides special support for character strings via the java.lang.String class. Enclosing your character string within double quotes will automatically create a new String object; for example, String s = “this is a string”;,
Is double and float the same in Python?
Integers – When you type a=3 at the prompt, python interprets the number 3 as an integer. This is probably what you want, but it might lead to arithmetic results that surprise you. Consider the following python commands. >>> a = 3 >>> a/4 0 >>> float(a)/4 0.75 When python does arithmetic with integers, it always truncates the result to an integer. Thus in python, 3/4=0, If we want to get decimal answers, at least one number in the computation must be in a floating point representation. We can convert integers to floating point numbers in python using the float and double functions. These are almost the same – two names are provided because in some programming languages there are differences between float and double types. There are no such differences in python, but note that float is built in to python, while double comes from numpy, and hence is slightly different. Interestingly, it turns out that the double function is somewhat slower than float, >>> from numpy import * >>> a=3 >>> 1/a 0 >>> 1/float(a) 0.3333333333333333 >>> 1/double(a) 0.33333333333333331 By the same token, we can truncate floating point numbers to integers in python using the int command. >>> pi 3.141592653589793 >>> int(pi) 3