x += 1 # Shorthand for x = x + 1 捕获异常 Python当中使用try和except捕获异常,我们可以在except后面限制异常的类型。如果有多个类型可以写多个except,还可以使用else语句表示其他所有的类型。finally语句内的语法无论是否会触发异常都必定执行: # Handle exceptions with a try/except block try: # Use "rai...
One line if statement:if a > b: print("a is greater than b") Try it Yourself » Related Pages Python If...Else Tutorial If statement If Indentation Elif Else Shorthand If Else If AND If OR If NOT Nested If The pass keyword in If ...
shorthand.py 示例: #!/usr/bin/env python3N =100a =2whilea < N:print(str(a)) a *= a 运行之: $ ./shorthand.py 2 4 16 5. 表达式 通常我们书写表达式的时候,会在每一个运算符左右都放一个空格,这样使代码更可读,如: a =234* (45-56/34) 一个用于展示表达式的例子,注意其中运算符的优...
捕获异常try..except..else 注意:except子句的数量没有限制,但使用多个except子句捕获异常时,如果异常类之间具有继承关系,则子类应该写在前面,否则父类将会直接截获子类异常。放在后面的子类异常也就不会执行。 格式: try: 可能触发异常的语句块 except [exceptionType]: 捕获可能触发的异常[可以指定处理的异常...
else: 没有触发异常时,执行的语句块 try的工作原理: 执行一个try语句时,python解析器会在当前程序流的上下文中作标记,当出现异常后,程序流能够根据上下文的标记回到标记位,从而避免终止程序。 1. 如果try语句执行时发生异常,程序流跳回标记位,并向下匹配执行第一个与该异常匹配的except子句,异常处理完后,程序流就...
prints: 0 1 2 3 """ x = 0 while x < 4: print(x) x += 1 # Shorthand for x = x + 1 捕获异常 Python当中使用try和except捕获异常,我们可以在except后面限制异常的类型。如果有多个类型可以写多个except,还可以使用else语句表示其他所有的类型。finally语句内的语法无论是否会触发异常都必定执行:...
判断 if expression1: if_suite elif expression2: elif_suite else: else_suitewhile循环 while expression: while_suitefor循环 for eachNum in [0,1,2]: print eachNumfor循环 for eachNum in range(3): print eachNum列表解析 squared = [x**2 for x in range(4)]...
close() if __name__ == '__main__': fileName = '/usr/local/src/pyScript/fileOperation.txt' dic = {'name':'Jmilk','age':'23','city':'BJ'} if os.path.exists(fileName): write_test(fileName,dic) else:print('File not exist!') 注意:try..finally与try..except 是可以同时使用...
This syntax makesdecorator()automatically takedecorated_func()as an argument and processes it in its body. This operation is a shorthand for the following assignment: Python decorated_func=decorator(decorated_func) Here’s an example of how to build a decorator function to add new functionality to...
if (n := len(string)) < 8: ... print(f"Length {n} is too short, needs at least 8") ... else: ... print(f"Length {n} is okay!") ... >>> validate_length("Pythonista") Length 10 is okay! >>> validate_length("Python") Length 6 is too short, needs at least 8 ...