Python Exception Handling: Graceful Error Management in Code

If you have some suspicious code that may raise an exception, you can defend your program by placing the suspicious code in a try: block. After the try: block, include an except: statement, followed by a block of code which handles the problem as elegantly as possible.

• The try: block contains statements which are susceptible for exception

• If exception occurs, the program jumps to the except: block.

• If no exception in the try: block, the except: block is skipped.

Syntax

Here is the simple syntax of try...except...else blocks −

Here are few important points about the above-mentioned syntax −

• A single try statement can have multiple except statements. This is useful when the try block contains statements that may throw different types of exceptions.

• You can also provide a generic except clause, which handles any exception.

• After the except clause(s), you can include an else clause. The code in the else block executes if the code in the try: block does not raise an exception.

• The else block is a good place for code that does not need the try: block's protection.

Example

This example opens a file, writes content in the file and comes out gracefully because there is no problem at all.

It will produce the following output −

Written content in the file successfully

However, change the mode parameter in open() function to "w". If the testfile is not already present, the program encounters IOError in except block, and prints following error message −

Error: can't find file or read data


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