string 拼接

能够应用 + 实现两个字符串的拼接。

a = "Hello"b = "World"c = a + bprint(c)--- output ---PS E:\dream\markdown\python> & "C:/Program Files (x86)/Python/python.exe" e:/dream/markdown/python/app/app.pyHelloWorld

如果想调整一下格局，能够在 hellworld 之间加上空格，如下所示：

a = "Hello"b = "World"c = a + " " + bprint(c)--- output ---PS E:\dream\markdown\python> & "C:/Program Files (x86)/Python/python.exe" e:/dream/markdown/python/app/app.pyHello World

string 格式化

还记得在后面的文章中提到，将 string 和 int 进行拼接是行不通的，这时候的解决方案就是用 format ,先看一下之前的例子。

age = 36txt = "My name is John, I am " + ageprint(txt)--- output ---PS E:\dream\markdown\python> & "C:/Program Files (x86)/Python/python.exe" e:/dream/markdown/python/app/app.pyTraceback (most recent call last):  File "e:/dream/markdown/python/app/app.py", line 2, in <module>    txt = "My name is John, I am " + ageTypeError: can only concatenate str (not "int") to str

接下来看看 format，在字符串中设置一个占位符 {}，占位符的参数通过 format 传入，如下所示：

age = 36txt = "My name is John, and I am {}"print(txt.format(age))PS E:\dream\markdown\python> & "C:/Program Files (x86)/Python/python.exe" e:/dream/markdown/python/app/app.pyMy name is John, and I am 36

有些敌人可能就要问了，既然反对一个 占位符，那能不能反对多个占位符呢？ 当然能够啦，如下所示：

quantity = 3itemno = 567price = 49.95myorder = "I want {} pieces of item {} for {} dollars."print(myorder.format(quantity, itemno, price))--- output ---PS E:\dream\markdown\python> & "C:/Program Files (x86)/Python/python.exe" e:/dream/markdown/python/app/app.pyI want 3 pieces of item 567 for 49.95 dollars.

除了这种通用的占位符，还能够应用相似 C# 中的数字型占位符模式，实现精准指向性占位。

quantity = 3itemno = 567price = 49.95myorder = "I want to pay {2} dollars for {0} pieces of item {1}."print(myorder.format(quantity, itemno, price))--- output ---PS E:\dream\markdown\python> & "C:/Program Files (x86)/Python/python.exe" e:/dream/markdown/python/app/app.pyI want to pay 49.95 dollars for 3 pieces of item 567.
译文链接：https://www.w3schools.com/pyt...

更多高质量干货：参见我的 GitHub: python