The reason why a computer can do many automated tasks is because it can make conditional judgments on its own.
output result
- Note: Indentation rules for Python code . Code with the same indentation is considered a code block, and the above 3 or 4 lines of print statements constitute a code block (but not the print on line 5). If the if statement evaluates to True, the block of code will be executed.
- For indentation, please strictly follow the habit of Python: 4 spaces, do not use Tab, and do not mix Tab and spaces , otherwise it is easy to cause grammatical errors caused by indentation.
- Note: An if statement is followed by an expression and then a : to indicate the start of a block of code.
- If you are typing code in a Python interactive environment , pay special attention to indentation , and you need to type an extra line of carriage return to exit the indentation:
When the if statement evaluates the expression to be True, the block of code contained in the if is executed:
Using the if...else... statement, we can execute the if code block or the else code block respectively according to the value of the conditional expression being True or False.
Note: there is a ":" after the else
To avoid if...else... in nested structures, we can use if... multiple elif...else... structures and write all the rules at once :
Special Note: This series of conditional judgments will be judged from top to bottom. If a judgment is True, the corresponding code block will be executed, and the subsequent conditional judgments will be ignored and will not be executed .
For more details, please see http://note.youdao.com/noteshare?id=ddd78caf8d8d195e4c66d24a4fb5f862&sub=EDA7F9C87FF7454DA80DA9F046EE7975