Len和Print Len()之间的区别 [英] Difference between Len and Print Len()
问题描述
我最近开始用Python进行数据分析，因为我没有从头开始学习Python，所以我觉得我错过了一些细微差别.
I've recently started doing data analysis in Python and since I didn't learn Python from scratch I feel I've missed a few nuances.
我注意到的一件事是，在我的一份报告中，我从CSV导入了一个数据集，将其作为字典放入其中，对其进行了处理，并试图打印其余条目.
One thing I noticed is in one of my reports I had imported a data set from a CSV, put it in as a dictionary, manipulated it and was trying to print the remaining entries.
我用过:
len(a)
len(b)
len(c)
执行此操作时，仅返回一个数字，因此我花费了大量时间调试我的代码.最后，我在网上找到了类似的代码，并尝试复制其语法.有效的更改是:
When I did this only one of the numbers was returning and so I spent a significant amount of time debugging my code. In the end I found similar code online and tried to copy its syntax. The change that worked was:
print len(a)
print len(b)
print len(c)
我试图了解这两个命令之间的区别.最初，我认为len只是打印出一个计数，但是我猜它有所不同吗?
I'm trying to understand the difference between the two commands. Initial I thought len just printed out a count, but I guess its something different?
len的计数只有记忆"吗?为什么我需要添加打印?
Does len only have 'memory' for one count? Why do I need to add print?
推荐答案
len(list)不打印任何内容，仅返回.如果您正在使用REPL(读取-评估-打印-循环)，则它将打印返回的值并循环.因此，要打印多个，必须调用print.
len(list) does not print anything, it only returns. If you are using REPL (read - evaluate - print - loop) then it will print the returned value and loop. Therefore to print more than one you must call print.
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