这里statement1和statement2两个变量都为字符串,但是quantity这个变量为整数,因此print statement1 + quantity + statement2会报错TypeError: cannot concatenate 'str' and 'int' objects, 提示不能将字符串和整数拼接合并。解决的办法是使用str()这个函数将quantity从整数转化为字符串,举例如下: ...
we have a technique calledMnemonic(记忆的).The idea is when you choose a variable name,you should choose a variable name to be sensible and Python doesnt care whether you choose mnemonic variable names or not. Assignment Statements: An assignment statement consists of an expression on the right...
If a variable name appears on the left hand side of an assignment, but is not declared global, it is assumed to be local. If it does not appear on the left hand side of an assignment, it is assumed to be global. >>> import dis >>> def foo(): ... global bar ... baz ...
A common use of the conditional expression is to select variable assignment. For example, suppose you want to find the larger of two numbers. Of course, there is a built-in function, max(), that does just this (and more) that you could use. But suppose you want to write your own co...
In Python, theequal sign (=) assigns a variable to a value: >>>count=4>>>count4 This is called anassignment statement. We've pointed the variablecountto the value4. We don't have declarations or initializations Some programming languages have an idea ofdeclaring variables. ...
决策制定;也就是if语句 循环语句;也就是for和while循环 函数 模块 技术要求 在阅读本书之前,您应该了解 Python 编程的基础知识,比如基本语法,变量类型,元组数据类型,列表字典,函数,字符串和方法。在python.org/downloads/上有两个版本,3.7.2 和 2.7.15。在本书中,我们将使用版本 3.7 进行代码示例和包安装。
We know from before that each variable name belongs to a certain abstract environment or namespace,and we can think of it as a context in which a given name exists. 我们从前面就知道,每个变量名都属于某个抽象环境或名称空间,我们可以将其视为给定名称所在的上下文。 This is analogous to many eve...
You need to use==for comparison tests, not=(which is for variable assignment). ifneeds to be lowercase. Remember that Python is case-sensitive. However, youshouldbe usingelifandelsehere since no two of those expressions could ever beTrueat the same time: ...
(which appears when a command is not complete) is`...'.The prompts can be changed by assignment to sys.ps1 or sys.ps2.The interpreter quits when it reads anEOFat a prompt.When an unhandled exception occurs,a stack trace is printed and control returns to the primary prompt;innon-...
In the assignment statement where you define first_half, you use the slice that represents the items from the beginning of numbers up to the midpoint. You can work out what the slice represents by breaking down the steps you use in the slice expression: First, len(numbers) returns the int...