Welcome to chapter 9 of our python tutorial. In the previous chapter, we looked at frequent examples of invalid Python syntax and learned how to fix them. Up to this point, you are well aware of errors that may occur in your Python program and how you can solve them easily and quickly. Therefore, in this tutorial, we will look at a few more causes of syntax errors and zero-error divisions.
Mistaking Dictionary Syntax
As you learned before, omitting the comma from a dictionary element can result in a syntax error. In Python dictionaries, the equals symbol (=) is used instead of a colon to separate key and value pairs.
This error message is once again useless. In this case, the repeated line and caret come in handy! All signs lead to the main antagonist. In addition, if you mistakenly believe that defining a dictionary is the same as calling dict(), you'll get this error. A colon could be used in place of the equals sign to correct this. It's also possible to use dict() instead:
If the dict() syntax is more useful, you can use it to define the dictionary.
Using the Wrong Indentation
Syntax Error has two subclasses that deal especially with indentation issues:
- Indentation Error
- Tab Error
Python employs whitespace instead of curly brackets to represent blocks of code in other computer languages. Python, on the other hand, assumes that your code's whitespace will behave predictably. If a line in a code block has an incorrect number of spaces, an Indentation Error will be thrown:
A quick inspection may not reveal that line 5 is indented by two spaces. It should be four spaces over from the for-loop expression. Fortunately, Python can detect this and instantly inform you of the problem. However, there's some gray area here as well. Do you want the print("done") to appear before, or after the block with a for-loop? if you run the following code, you'll get the following error message;
It appears like a Syntax Error traceback, but it is an Indentation Error. Error messages are also highly helpful. There is a discrepancy in the line's indentation level compared to other indentation levels. Print('done') is an alternative that is indented by two spaces, but Python can't identify any additional lines of code that match this amount of indentation. To resolve the problem quickly, make sure the code is aligned with the anticipated indentation level. Tab Error is another type of Syntax Error, which is the result of indentation using tabs or spaces, while the rest of the file has either spaces or tabs instead. You may not see this until Python does!
All lines may be indented at the same level when the tab width is the same as the number of spaces used in each indentation criterion. For example: Using tabs instead of spaces when indenting a line will cause Python to raise an error message.
Instead of four spaces, a tab denotes indentation on line 5. Depending on your system, this code block may appear correct to you, or it may appear incorrect to you.
Python, on the other hand, will be alerted to the problem right away. As a way to view whatever Python tells us is wrong; it might be beneficial to view an example of what the code looks like under various tab-width settings:
The three examples above show a considerable difference in how they are shown. Even though most of the code utilizes four spaces per level of indentation, Line 5 only uses one tab in all three circumstances. The width of the tab changes when the tab width is set:
The print statement will appear to be outside the for loop if the tab width is set to 4. After the loop, the console will display the word 'done. If the tab width is set to 8, the print statement will appear to be inside the for loop (which is common on many computers). After each number, the console will display the word 'done.' Using the print statement with a tab width of 3 appears strange too. In this case, there is no indentation level associated with line 5.
There is a traceback and error message when you run this code.
Instead of a Syntax Error, there's a Tab Error. A useful error message from Python identifies the problematic line. It's easy to see that the file contains a mix of tabs and spaces for indentation. There is no need to utilize both tabs and spaces in the same Python code file as a workaround. It would be better if we replaced the tab with four spaces, which would output "done" when the for loop completes.
Function Definition and Invocation
When defining or calling functions in Python, you may encounter syntax errors. If at the end of a function definition, you place a semicolon instead of a colon, you'll get a Syntax Error.
With the caret pointing directly at the problematic character, this traceback is helpful. The semicolon can be replaced by a colon in Python to correct this erroneous syntax. As an additional requirement, keyword arguments must be placed in the correct sequence in both function definitions and function calls. Positional arguments are always followed by keyword arguments. A Syntax Error will be thrown if this ordering is not followed:
Again, the error notice makes it quite clear what went wrong with the line in question.
Updating Your Python Software
When upgrading from one version of Python to another, it's not uncommon for previously working code to malfunction. This is the result of standardized grammatical adjustments. Most notable is the print statement, which was a keyword in Python 2 but was converted to a built-in function in Python 3.
The Syntax Error's error message shines in this case! It also informs you exactly how to fix a print call that has missing parenthesis. Additionally, it's possible to come across syntax that is correct in one Python version but is not correct in the one you're working in. The f-string syntax, for example, does not exist in Python before 3.6:
Before Python 3.6, the interpreter had no concept of the f-string syntax and would simply produce an error stating that the syntax was invalid. Python version 2.7 was used in this example, and while the code seemed to be correct, it was running on an older version. Double-check the Python version you're using if you're unsure.
The new Syntax Warning is also included in Python 3.8. This alert will appear if the syntax is correct, but there is something fishy about it. A comma would be needed between two tuples in a list as an illustration of this. Because a tuple cannot be called, this code would trigger a Type Error in earlier versions of Python.
The Python interpreter interprets your attempt to use a tuple as a function, which results in this Type Error.
This code still raises a Type Error in Python 3.8, but now you'll see a Syntax Warning that tells you how to solve it.
New Syntax Warning even includes a clue ("maybe you skipped a comma?") to put you in the right way!
What are ZeroDivisionErrors?
It's possible to get a ZeroDivisionError when you divide by zero. In mathematics, an integer split by zero yields an infinite number. Infinite numbers are physically impossible to write down. A ZeroDivisionError: division by zero "is thrown by Python if the result is infinity. It is possible to divide two numbers by one another. A division procedure is all about dividing an int or float value into equal parts or groups. It's harder to interpret a number when it's broken into zeroes. When a number is divided by zero, the outcome is unclear.
Infinity is the result of dividing a number by zero. Since an infinite number cannot be expressed in a concrete form, Python cannot handle it. A "ZeroDivisionError: division by zero" is thrown in this case by Python. The following is an example of an error that would be thrown if it occurred.
Errors of varying severity
Python's Zero Division Error can be thrown in many different ways. The following is a list of ZeroDivisionError's various forms.
What is the cause of the problem?
Zero-division errors occur when numbers are divided by zero or when they are modulo zero. A non-zero numeric number should be used as the denominator in the division operation. If the denominator is 0, the interpreter throws the exception ZeroDivisionError. It is illogical to divide a number into units of zero. So, you end up with an unrepresentable, infinitely large integer in Python. Python throws an exception because of the "ZeroDivisionError: integer division or modulo by zero" error. An integer, long, float, or complex number can all be affected by this issue.
How can we replicate this problem?
It is necessary to divide an integer by a non-zero number. ZeroDivisionError is thrown by the Python interpreter when a number is divided by zero in a program. A division error will occur if the numerator is set to 0.
The code that follows demonstrates how to get the error to occur again.
x = 8
y = 0
z = x / y
print z
Results:
Solution 1
In Python, zero cannot be divided by anything. The denominator must be nonzero before performing any division or modulo operations. When the denominator is 0, the code below explains how to handle it.
x = 8
y = 0
z = x / y
print z
Results:
Solution 2
Denominator values can be zero in some circumstances when the program is uncertain about the denominator value. Handle the ZeroDivisionError if it occurs in this situation. Using the code below, you can see how to handle a ZeroDivisionError.
try:
x = 8
y = 0
z = x / y
except ZeroDivisionError:
z = 0
print z
Output:
Solution 3
The output of a division operation can be set to zero if the numerator is 0 in the program. This may not be correct in terms of mathematics. Real-time calculations will no longer have this problem if the division is set to zero. Here's how to establish the zero for the division operation using this code.
x = 8
y = 0
if y == 0:
z = 0
else:
z = x /y
print z
Output:
At this point, you might have met or heard the term debug somewhere during your programming journey.
What is debugging?
As a multi-step process in computer programming and engineering, debugging begins with the discovery of an issue before being followed by an attempt to isolate the problem's cause and either resolve it directly or find an alternate solution. Finally, a patch or workaround must be tested to see if it fixes the problem. The debugging process has two stages: the discovery of a bug and the ability to replicate it. It is necessary to include debugging in every stage of software development and testing.
Debugging in hardware development often focuses on finding hardware components that are incorrectly installed or configured. A JTAG connection test, for example, could be used by an engineer to look for bad connections on a computer chip.
Conclusion
You've seen how the Syntax Error traceback provides you with information in this tutorial. Several frequent Python syntax problems have been demonstrated, along with solutions. In addition to speeding up your work, this will make you a better code reviewer because you will be able to do more. It is highly recommended that you use an editor that understands Python syntax and provides feedback as you write code. To make sure you don't write any bad Python code, look at the examples from this course in an IDE before you start writing your own. When studying Python, a syntax error can be frustrating, but now you know how to comprehend traceback warnings and what sort of erroneous Python syntax you may encounter. You'll be more prepared for the next time you encounter a syntax error!
