python 中 type() 转换的问题 3

Question

name = input("what is your name : ")
age = int(input("what is your age : "))
age_after_100_years = 2021 + (100-age)
print(name + " your age after 100 years is " + age_after_100_years)

in the above code on line 2, ive converted the string to int and then used it in "age_after_100_years" variables, but it gives me an error

Output:
what is your name : p
what is your age : 25
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-3-565602469d9c> in <module>
  2 age = int(input("what is your age : "))
  3 age_after_100_years = 2021 + (100-age)
----> 4 print(name + " your age after 100 years is " + age_after_100_years)

TypeError: can only concatenate str (not "int") to str

但是当我在第 3 行使用 str() 时，即

name = input("What is your name? : ")
age = int(input("What is your age? : "))
age_after_100_years = str((2022-age)+100)
print(name+" you will be 100 years old by the year "+age_after_100_years)

Output:
What is your name? : pratik
What is your age? : 25
pratik you will be 100 years old by the year 2097

以上代码有效，

正如我想知道的，我已经将变量“age”中的字符串转换为 int()，那么为什么我必须将变量“age_after_100_years”转换为 str()，如果我“age”变量是 int()，“age_after_100_years”以 int() 输入开头，我将 int 与 int 输入连接起来？

Answer 1

变量“age_after_100_years”是整型，所以如果要使用“+”运算符将其连接到另一个字符串，则必须将其转换为字符串。

Answer 2

Python 中的 + 运算符对数值进行加法运算（例如，1 + 2 = 3），但它对字符串进行连接（"1" + "2" = "12"）。根据 Python 告诉您的内容，您正试图 + 一个字符串和一个数字，这是不允许的。相反，您需要在进行连接之前将数字转换为字符串值 (str(number_variable))。

或者，正如其他人指出的那样，使用 f 字符串，它允许您将数字（或任何其他支持 str() 的 types/objects）替换为字符串表达式（实际上，任何东西，但是，如果您在尚未为 str() 方法实现接口的 BinaryTree class 上调用 str()，则可能会得到诸如 "BinaryTree object at 0x0454354" 之类的文本。

看看你的例子，你可能想做：

name = input("What is your name? : ")
age = int(input("What is your age? : "))
age_after_100_years = str((2022-age)+100)

# passing multiple parameters to print()
print(name, " you will be 100 years old by the year ", age_after_100_years)

# using string concatenation
print(name + " you will be 100 years old by the year " + str(age_after_100_years))

# using f-strings
print(f"{name} you will be 100 years old by the year {age_after_100_years}")

# using %-formatting
print("%s you will be 100 years old by the year %s" % (name, age_after_100_years) )

# using string.format()
print("{} you will be 100 years old by the year {}".format(name, age_after_100_years) )

所有人都应该完成工作，但 f 弦更简洁、更短且更易于阅读:)

Answer 3

friend 你的代码 id 给出了一个错误，因为其中的 age 变量是 int 类型，而在下一行你将连接不允许的 int 所以我已经更正了你的代码并在更正后这是代码

name = input("what is your name : ")
age = int(input("what is your age : "))
age_after_100_years = 2021 + (100-age)
print(name , " your age after 100 years is " , age_after_100_years)

之后的结果是

what is your name : p
what is your age: 12
p  your age after 100 years is  2109

python 中 type() 转换的问题 3

Question with type() conversion in python 3

python

python-3.x

python-3.8