what is python expression

Python expressions are a combination of values, variables and operators (or operators). A single value is an expression, and a single variable is an expression.

Operators and operands together form an expression. The operands can be represented by identifiers, such as a=3;b=2;c=a*b, and the expression is a python program The most common code

Python code consists of expressions and statements and is executed by the Python interpreter. (Recommended learning: Python video tutorial)

The main difference between them is that "expression" is a value, and its result must be a Python object. The result can be any object when the Python interpreter evaluates it. For example, 42, 1 2, int(‘123’), range(10), etc.

Priority of expressions

Expressions have priorities. The simplest ones are the mathematical calculations in our assignment operator: "0 * 1 2" and "0 1 * 2" "The results must be different. In "0 1 * 2", "1 * 2" is calculated first.

Of course, not only assignment operations have priority, but there are also priorities among various operators.

#在下面这个运算中，假设a、b、c都是ture值，因为and 的优先级大于 or ,所以最后结果是a#
>>> a or b and c
a
 
#在下面这个运算中，假设a、b、c、d都是ture值#
#因为 + 的优先级大于 and 大于 or ,所以最后结果是a + b的结果#
>>> a + b or c and d
a + b
 
#用括号表现优先级就是:先运行a + b,再运行c or d 得到 d ,最后运行(a+b) or d#
>>> (a + b) or (c and d)
a + b

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