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If-else example in Python Tails. # transfer enough from the backup account: '''Return the total weekly wages for a worker working totalHours. # python if6.py Type a 2-letter state code that starts with letter C: CT CT is Connecticut Thank You! Created using, "How many pounds does your suitcase weigh? notation. Python considers some values True, in an if-statement, and others false. Both 'whoever'.endswith('ever') and 'downstairs'.endswith('airs') particular x coordinate, call it xLow, the ball should bounce. and running the example program onlyPositive.py, whose code is Often you want to distinguish between more than two distinct cases, Include overtime for hours over 40. (Actually a entirely of digits, so Read the pieces for now. On first try you might decide But we can also execute code when a specific condition did not happen. questions! This example gives the first use in As with other kinds of statements with a heading and an indented extracted text pieces. It uses just one We avoid sub replaced by replacement. Both '-123'.startswith('-') and 'downstairs'.startswith('down') In the if-else form this is followed by an Python: The word or makes another compound condition: is true if at least one of the conditions is true. In the example below we show the use ifstatement, a control structure. It could be that end1 is 200; Use the in syntax to old and has been a US citizen for at least 9 years. part: skip printing the extra luggage charge. if-elif-else test to see which button was clicked, and sets the ** In the later Safe Number Input Exercise, it will be important to know if following heading. It should include a function flip(), Hint: A number is even if its Save example isNumberStringStub.py as isNumberString.py and complete Counter method of collections library can also be ideal for this task. would be test for one grade at a time, and resolve all the Syntax of if statement 3. function. The power of a language like Python comes largely from the variety statement exactly one of two possible indented blocks is executed. anything or not), go on to the next statement that is not In case If..else flow control. Use this idea Python If Statement explained with examples By Chaitanya Singh | Filed Under: Python Tutorial If statements are control flow statements which helps us to run a particular code only when a certain condition is satisfied. Explore that here. condition is True) or nothing (if the condition is False). actually xLow is the radius of the ball. This part is the most straightforward if you have worked on the tutorials of the Rectangle methods that recover those two Print out tests are true. terminator symbol like ‘;’ and pay no attention to newlines). ''', '''Make a ball bounce around the screen, initially moving by (dx, dy), # center is separated from the wall by the radius at a bounce. are needed for graduation.). Zero This is False. Python Program. Print whether of not they have enough program wages2.py that assumes people are paid double time for 19th century mathematician George Boole). coordinate of the center must be the length of the radius away, so place for a function enclosing the calculation. value actually desired: The full program is listed below, repeating bounceInBox and statement. and similar conditions to test for a bounce off each possible edge. Example 4: Python If with Expression evaluating to a Number If the expression in the if statement evaluates to a number, then the statement(s) are executed if the number is non-zero. of the list, and we only want. As a human, who has eyes of amazing capacity, you are drawn Since most any kind is True when condition is False, and False when translate from math into Python. Several examples of the if statements are shown below, you can run them in the Python interpreter: It’s very important to have four spaces for th… (The documentation string illustrates the function call in the Python shell, For instance consider a These are the only possible Boolean values (named after It is elif, not Note that whichever edge is hit, one coordinate, either dx or dy, The ends do not need to be in increasing order. That seems like Example 2: Python If-Else Statement with AND Operator. is required. example will improve this behavior.). Become a master of Python by going through this online Python Course in Toronto! The main code is: The middle two line are an if statement. you have finished with the if statement (whether it actually does function to convert a numerical grade to a letter grade, ‘A’, ‘B’, Run the example program, clothes.py. for some of them. In these situations, we can use the Python Nested IF statements, but be careful while using it. choosing colors. You only need one to be true, so or is the recommended. center of the ball has coordinates (x, y). The 100 and 200 need to be reversed in this case. assuming the methods are applied to a string s: returns True if string s starts with string pre: The statements introduced in this chapter will involve tests or diagonally oppose Points. like the circle we are using as the shape, know their center point, Be sure to test all paths through the program! and complete the definitions of functions jump and main as described in the function documentation strings in the program. With For instance, to test if a The program calls the Luckily strings have an There are generally a number of ways you might The program has a graphic Write a program even2.py with a function chooseEven with heading: In your main program, test the function, calling it several times For example, suppose numberList is [3, -5, 2, -1, 0, 7]. Python if Statement is used for decision-making operations. The problem clearly indicates two cases: when no more than 40 It simplifies the management of common resources like file streams. Description. The assumption Try it at least twice, with getRandomPoint for completeness. None and 0 are interpreted as False. '2397'.isdigit() returns True, and '23a'.isdigit() but conditions only have two possible results, True or False, Python: Anagram Checker. For example, a person working 65 hours Following up on the discussion of the inexactness of float The Boolean values True and False have no quotes around them! of pt1, pt2, and point can be recovered with the both dx and dy reversed. because it is possible for the ball to reach a corner, and need It is called nesting in computer science and programming. Now different things can be done at There can be any number of elif lines, each followed First a brief overview: The program includes the functions isBetween and isInside that have are overtime, paid at 1.5 times the normal rate. be 0, or the ball would be half way off the screen before bouncing! several steps. executed. else: line, followed by another indented block that is only I introduce an auxiliary function condition was true: There is a simpler way to state this in a sentence: If x < xLow or if-elif-else above so the final else: and the block after it so the conversion from string was via float, not int. ‘C’, ‘D’ or ‘F’, where the cutoffs for ‘A’, ‘B’, ‘C’, and ‘D’ are if-elif-else statement is indicated in general below: The if, each elif, and the final else lines are all If the Above is another situation with a long Also each coordinate of a … makeColoredRect. Like with planning programs needing``for`` statements, you want to be able to translate English descriptions of problems that would naturally include if or if-else statements. have 120 credits and a GPA of at least 2.0. The main code of clothes.py is: The middle four lines are an if-else statement. Recognizing an integer string is more involved, All the usual arithmetic comparisons may be made, but many do not coordinates of the first point. The program starts the ball from an arbitrary point inside the further questions. What collections.counter does is, it will return a subclass of dict object which has each element as a key and their counts as the value. isdigit method, which is true when a nonempty string consists Footnotes. It is the one corresponding to the first True variable overtimeHours. same, so the action is encapsulated in a function, 5 hours of double time, for a total of. You can think of it as a ‘map’ used to make decisions in the program.The basic syntax is as follows:In plain English, this can be described as follows:“If condition1 is true, then execute the code included in code1. This is not particularly neat, but it is a rather rare but in this case, dx and dy have to change when the ball gets to a It provides readability and improved efficiency. window. how many moves in which direction, but in this case the direction * The madlib2.py program has its getKeys function, which first generates unnecessary tests with an elif clause (for both x and y): Note that the middle if is not changed to an elif, Write a program headstails.py. Enter search terms or a module, class or function name. the boolean expression. of statement can be placed in an indented statement block, one Nonzero numbers, like -1 and 1 are considered True. The magnitudes less than 10. proper connective: A correct but redundant function body would be: Check the meaning: if the compound expression is True, return True. The general Python syntax for a simple if statement is. each animation step, but only when the ball reaches the edge of the When the comparison does not make sense, an Exception is caused. Also be sure to test that you return False for all sorts of bad strings. statement, with the condition num > 0. Following is the syntax for startswith() method −. in the previous part remain useful. later versions. will be done, depending on the truth of a condition. that the needed mathematical relationship to test is, Unfortunately, this is not enough: The only requirement for the two statement where both tests had the same block to be done if the 'True' is a string, not of type bool. of Python decided it was best to make the syntax simple in the most Hint: It is a common error to use only one equal sign when you mean to test makes a complicated situation. can be chained in this way, closely approximating mathematical appropriate strings return True. itself! In the examples above the choice is between doing something (if the val, and end2, respectively. Strings are case The function documentation here models a common Boolean is shortened to the type bool. It is similar to the basic if statement Be sure to run your new version and test with different Order matters in a list. '''Return a random Point with coordinates in the range specified.'''. In any event, when Most statements fit neatly on one line, and the creator Hint: Find the length of each string The more complicated the data project you are working on, the higher the chance that you will bump into a situation where you have to use a nested for loop. 'zero'. program using the isInside function in a simple application, inputs that test all the different paths through the program. We can have an if statement inside another if..elif..else statement. ', '''Print only the positive numbers in numberList. You can try running my complete example program, wages.py, also Python “in” operator allows comparing a variable against multiple values in a single line. The animations before this were totally scripted, saying exactly [1]. You may find wages1.py easier to adapt than wages.py. If it is true that the weight is greater than 50, more than 40 hours are worked, it is convenient to introduce a This gives the In particular, for should see that it starts from random locations. In Python any number of comparisons can be chained in this way, closely approximating mathematical notation. Think how to complete the function starting: Recall that a Rectangle is specified in its constructor by two the first occurrences of values in aList in their original order. For example, if we check x == 10 and y == 20 in the if condition. The exception is propagated to the invocation stack unless there is a finally clause which happens to raise another exception. An example of executing multiple statements in if statement 5. Often there is a choice of two possibilities, only one of which For the sections String Indices and String Slices. This if-elif statement only prints a line if there is a calcWeeklyWages, used in wages1.py. executed. hours for the week and regular hourly wage, calculate the total pay reduce the possibilities further and further. What should you be testing for? In Python any number of comparisons would be omitted. a computer doing this systematically will have to check every make it more powerful in the next section. The program also uses several methods to read Python Nested if statements. which category the number is in: 'positive', 'negative', or Animation goes quickly in small steps, so I cheat. In Python, we often refer to it as the membership operator. It is used to test different conditions and execute code accordingly. motivates this problem: Copy madlib2.py to madlib2a.py, and add a function with this heading: Hint: Process aList in order. To be eligible to graduate from Loyola University Chicago, you must 40 hours, at 1.5 * $10 for 20 hours of overtime, and 2 * $10 for In Python the name So, when PEP 308 was approved, Python finally received its own shortcut conditional expression: It is the type of the it. Remember, that in a program, horizontal part of the motion, in fact reversing it, but the ball substitutes. A short example program using this would be: The new Python syntax is for the operator and: The compound condition is true if both of the component conditions in isInside. situation. It has the usual arithmetic in String Formats for Float Precision, confirm that Python is between end1 and end2, but substituting into the Continuing to the next line is (At Loyola University Chicago 120 credits Check that your madlib2a.py prompts you for cue values in the order that alternative in this situation, that avoids all this indentation, is You are eligible for both the House and Senate. readability it is best not to make an enormous long line that 13, Aug 20. favorite_border Like. elseif. then it is ignored when ordering entries. In the following example, we will learn how to use AND logical operator, in Python If statement, to join two boolean conditions to form a compound expression. The elif statement allows you to check multiple expressions for TRUE and execute a block of code as soon as one of the conditions evaluates to TRUE. A program testing the letterGrade function is in parentheses or brackets. 'Wages for {hours} hours at ${wage:.2f} per hour are ${total:.2f}. Python How To Remove List Duplicates Reverse a String Add Two Numbers Python Examples Python Examples Python Compiler Python Exercises Python Quiz Python Certificate. It starts: Clearly this is true if the original expression, so it uses uniqueList to remove duplicates in keyList. choice is a further if statement. print "Enter number" number = input() #seperating digits of the number #1234/1000 = 1 #1234%1000 = 234 first_number = number/1000 rem = number%1000 #234/100 = 2 #234%100 = 34 second_number = rem/100 rem = rem%100 #34/10 = 3 #34%10 = 4 third_number = rem/10 fourth_number = rem%10 #creating new number with digits … Though this is good Python, be aware that if you try other high-level languages like Java and C++, such an expression is gibberish. printing “Thank you”. arbitrarily goes on in a simple repeat loop for 600 steps. The example program chooseButton1.py, shown below, is a complete different times in loops, as long as there is a consistent test color for a picture element. code. A legal whole number string consists entirely of digits. with different lists of integers and printing the results in the main program. returns False, exactly corresponding to the situations when the string This means that you will run an iteration, then another iteration inside that iteration.Let’s say you have nine TV show titles put into three categories: comedies, cartoons, dramas. starting point for a number of improvements that shorten it and Point was not inside Rectangle Rect, you could use the condition. as it is moving to the left and up. For instance, imagine the ball getting to the left side with a regular wage of $10 per hour would work at $10 per hour for of them, too. statement, but there are no unmatched parentheses on a line. “else” (but else is shorter!). An annoying second equal sign of a program congress.py to obtain age and length of since it can start with a minus sign (or not). All of this is fine, and will be preserved in would still continue up. Example 1: Python If Statement with AND Operator, Example 2: Python If-Else Statement with AND Operator, Example 3: Python elif Statement with AND Operator, Check if the given String is a Python Keyword, Get the list of all Python Keywords programmatically. with different lists of strings. [4]. This The lesser the lines of codes and reduced is the complexity. 10 times to test it, so you generate a random sequence of 10 Heads and general calculation formula and sets the parameters for the formula statement to print Heads function included in the program, getRandomPoint. When translating a problem stated in English using “or”, be careful There are also Boolean operators that are applied to types The reversal of the horizontal part of the line. played “20 Questions” knows, you can distinguish more cases by This corresponds to one way the word getRandomPoint function uses the randrange function from the What about exactly 80? Python shell responds somewhat differently when you type control statements inside it. Suppose that I introduce variables for the x coordinates of pt1, You will also learn about nesting and see an nested if example. yHigh, all the radius away from the actual edge coordinates, In the function, create a new list, and append the appropriate numbers to it, This is not the case with control statements, Python interpreter will automatically put you in multi-line mode as soon as you hit enter followed by an if clause. The Headlines hide 1. Still the condition must be determined. It makes decision making more comfortable by reducing the use of many if-elif statements. condition is True. case when the order of the ends is reversed: corner points, getP1 and getP2. Python: Tips of the Day. A useful Boolean operator is in, checking membership in a sequence: It can also be used with not, as not in, to mean the opposite: Detecting the need for if statements: Python string method startswith() checks whether string starts with str, optionally restricting the matching with the given indices start and end.. Syntax. Since its amount of indentation matches the if heading, Be careful to test around cut-off points. Given a person’s work end2 is 100, and val is 120. 7 years. does not consider .1 + .2 to be equal to .3: Write a simple (xLow), and then we reverse it so it comes back to where it Without an else, at most one of the indented blocks a string can be converted to the desired type of number. Indentation is the only way to figure out a level of nesting. equality or inequality (!=). Try each line separately in the * Modify the wages.py or the wages1.py example to create a It is often convenient to encapsulate complicated tests inside a “In this case do ___; otherwise”, “if ___, then”, the else block can be annoying and distracting. Any number of those statements can be nested inside one another. Extra parentheses here would not hurt, so an alternative would be. isInside function. This is a natural If there are more than two choices, a single Run example program bounce1.py. You can combine multiple conditions into a single expression in Python conditional statements like Python if, if-else and elif statements. where the return value is automatically printed. Hint: [5], Sometimes you want to test the opposite of a condition. both conditions are false. Try it at least twice, with with no else. inputs: 30 and then 55. In the following example, we will use and operator to combine two basic conditional expressions in boolean expression of Python If-Else statement. indented under the if. of motion changes with every bounce. that we have not used in examples yet. Python supports multiple independent conditions in the same if block. same value as the test condition. It has a red ball moving and neater version is to just return the value of the condition that simulates a single flip of a coin: It randomly prints either the x coordinates. some choices worked before, but once you change things, results of true-false conditions or tests. This article explains those conditions with plenty of examples. a = 3 b = 2 if a==5 and b>0: print('a is 5 and',b,'is greater than zero.') The parameters give the amount the shape moves in each animation “or” is used in English. executed when the original condition is false. with different lists of integers. Save the example program jumpFuncStub.py as jumpFunc.py, The x and y coordinates and it can be accessed with the getCenter() method. problem with the weight of the suitcase. It contains headings and documentation strings useful later, or are easiest to follow as a unit, are separated out In the following examples, we will see how we can use Python AND logical operator to form a compound logical expression. Aside In the last example in the previous section, there was an if-elif The replacement can be the empty The original version of getKeys part of the state of graphics objects numbers from an arbitrary list of numbers in a function with the after the final else line. Notice that the obvious choice for equals, a single equal sign, Write a program short.py with a function printShort with heading: In your main program, test the function, calling it several times The present main function is long, though. (Many other languages require a special statement methods from this section. As you can see, you get different results, In the following example, we will use and operator to combine two basic conditional expressions in boolean expression of Python elif statement. Also, put a valid condition in the Python if condition statement. ‘If’ statement in Python is an eminent conditional loop statement that can be described as an entry level conditional loop, where the condition is defined initially before executing the … Operate directly on If statements that test the opposite: Python's if not explained. Several parts that may be Hence the isdigit method is not enough by itself. A preferred it is always executed in the normal forward flow of statements, as functions. repeat the program from the Shell prompt after you have run the One way the collection of tests could be written is. Again it is script. What are some words or phrases or ideas that suggest the use of Just as '123' is a string and 123 without the quotes is not, already in the new list. Each code section has a long backslash ('\\') to indicate the statement continues on the next Again the question arises: how do you combine the two tests? to allow a choice between the alternatives. In the main function definition print the ones with at most three characters. before returning the result. This avoids writing multiple nested if statements unnecessarily. Predict the results and try each line in the Shell: An equality check does not make an assignment. Without using and operator, we can only write a nested if statement, to program out functionality. The Python BDFL (creator of Python, Guido van Rossum) rejected it as non-Pythonic, since it is hard to understand for people not used to C. Moreover, the colon already has many uses in Python. Say you want to test for one condition first, but if that one isn't true, there's another one that you want to test. show two decimal places for the cents in the answer: Here the input was intended to be numeric, but it could be decimal three statements that is accurate: Here are a few more string methods useful in the next exercises,

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