Conditional branching is a fundamental concept in programming that allows the execution of different blocks of code based on certain conditions. In Python, conditional branching is implemented using if, elif, and else statements.
The if statement is the most basic form of conditional branching in Python. It starts with the keyword "if", followed by a condition, and ends with a colon. The indented block of code that follows the if statement will be executed only if the condition is True.
For example, let's say we want to write a program that checks if a number is positive or negative:
num = 5 if num >= 0: print("The number is positive")
In this example, the condition "num >= 0" is True, so the indented code block will be executed and the output will be "The number is positive".
Sometimes, we want to execute different blocks of code based on different conditions. This is where the elif statement comes in. The elif statement is used after an if statement and checks another condition. If the previous condition was False and the current condition is True, the indented block of code under the elif statement will be executed.
For example, let's modify our previous example to add an elif statement:
num = -2 if num > 0: print("The number is positive") elif num == 0: print("The number is zero") else: print("The number is negative")
In this example, the condition "num > 0" is False, so the program checks the next condition "num == 0". This condition is also False, so the program executes the code block under the else statement, which outputs "The number is negative".
Finally, the else statement is used to execute a code block if all the previous conditions are False. The else statement is always the last part of a conditional branching structure and does not have a condition associated with it.
For example, let's modify our previous example again to remove the elif statement:
num = 0 if num > 0: print("The number is positive") else: print("The number is zero or negative")
In this example, the condition "num > 0" is False, so the program executes the code block under the else statement, which outputs "The number is zero or negative".
In conclusion, conditional branching is a powerful tool in programming that allows us to execute different blocks of code based on different conditions. The if, elif, and else statements in Python provide a simple and flexible way to implement conditional branching in our programs.