使用循环将值分配给列表中的变量 [英] Assigning values to variables in a list using a loop

问题描述

var_list = [one, two, three]
num = 1
for var in var_list:
    var = num
    num += 1

以上内容给我一个错误，提示一个"不存在.不能以这种方式分配吗?我想为列表中的每个var分配一个递增的数字.

The above gives me an error that 'one' doesn't exist. Can you not assign in this way? I want to assign an incrementing number for each var in the list.

推荐答案

Python变量是值的名称.它们并没有真正包含"这些值.

Python variables are names for values. They don't really "contain" the values.

for var in var_list:依次使"var"成为列表中每个元素的名称.在循环内部，var = num不会影响列表:相反，它会导致var不再是list元素的名称，而是开始成为任何num当前名称的名称.

for var in var_list: causes 'var' to become a name for each element of the list, in turn. Inside the loop, var = num does not affect the list: instead, it causes var to cease to be a name for the list element, and instead start being a name for whatever num currently names.

类似地，当您创建列表时，如果one，two和three还不是值的名称，则不能那样使用它们，因为您要创建一个列表.具有这些名称的值(然后使var_list为该列表的名称).请注意，该列表实际上也没有包含任何值:它引用(即共享它们).

Similarly, when you create the list, if one, two and three aren't already names for values, then you can't use them like that, because you are asking to create a list of the values that have those names (and then cause var_list to be a name for that list). Note that the list doesn't really contain the values, either: it references, i.e. shares them.

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