语句与表达式 Statements and Expressions Hint An expression is a data value or an operation that evaluates to a value. 对于表达式 它本身是值 它的计算结果是值 Hint Statements, by contrast, do not evaluate to a value, and we can't print them. Usually they perform some action, though. 对于语...
在一些其他语言中,^用来表示幂运算,但是在Python中,它是一个位运算符,叫做XOR。本书中没有涉及到位运算,但是你可以去维基百科阅读相关资料http://wiki.python.org/moin/BitwiseOperators。 在Python 2 中,除法操作符结果有时候并不是你需要的: >>> minute = 59 >>> minute/600 minute的值是59,通常59除以60...
2.5 表达式和语句(Expressions and statements) 表达式(expression)是集值、变量和运算符的式子。单独值本身也可视为一个表达式,同理变量也是。例如: x是已赋值的变量。 语句(statement)是Python解释器可执行的代码块。如print和赋值语句。严格来说,表达式也是语句,但其区别在于表达式有值,而语句没有。 2.6 交互模式和...
Chapter 2 Variables, expressions and statements 1)数值values和数值类型types 2)变量variables 变量就是引用数值的一个名字name,编程语言最强大的特点就是操作变量的能力。 # 1 赋值表达式 assignment statement # 2 赋值图 state diagram 3)变量名variable names 和 保留字keywords python中有29个保留字 4)语句sta...
You’ll start by using variables in expressions. Then, you’ll dive into counters and accumulators, which are essential for keeping track of values during iteration. You’ll also learn about other common use cases for variables, such as temporary variables, Boolean flags, loop variables, and ...
So, operators must be part of expressions, which you can build using Python objects as operands. So, what is an expression anyway? Python has simple and compound statements. A simple statement is a construct that occupies a single logical line, like an assignment statement. A compound ...
When you type a statement on the command line, Python executes it. Statements don't produce any result... index:: expression Evaluating expressions計算式子An expression is a combination of values, variables, operators, and calls to functions. If you type an expression at the Python prompt, ...
Lesson 2 - Expressions, Data Types, & Variables The Python programming language has a wide range of syntactical constructions, standard library functions, and interactive development environment features. Fortunately, you can ignore most of that; you just need to learn enough to write some handy lit...
You cannot step within a line of code to show how subexpressions get evaluated within that line; the best workaround is to manually split complex expressions into multiple lines and assign to temporary variables on each line (example).
If you have a programming background in another language, such as Java, you might have noticed that we didn't specify the variable type when we declared ourlengthandwidthvariables. Python doesn't require you to specify type, and you can change variable types freely. For example: ...