79 lines
2.1 KiB
Markdown
79 lines
2.1 KiB
Markdown
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---
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title: How to Convert Strings into Integers in Python
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localeTitle: 如何在Python中将字符串转换为整数
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---
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## 如何在Python中将字符串转换为整数
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就像内置的`str()`一样，Python也提供了一个方便的内置函数，它将一个字符串对象作为参数并返回相应的整数对象。
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#### 用法示例：
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```py
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# Here age is a string object
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age = "18"
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print(age)
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# Converting string to integer
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int_age = int(age)
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print(int_age)
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```
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产量
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```py
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18
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18
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```
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虽然输出在视觉上类似，但你应该记住，第一行打印一个字符串对象，而它旁边的行打印一个整数对象，这将在下一个例子中进一步说明：
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```py
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age = "18"
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print(age+2)
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```
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输出：
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```py
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Traceback (most recent call last):
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File "<stdin>", line 1, in <module>
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TypeError: cannot concatenate 'str' and 'int' objects
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```
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`The error should make it clear to you that you need to convert the`向其添加内容之前 `The error should make it clear to you that you need to convert the` age\`对象 `The error should make it clear to you that you need to convert the`整数。
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```py
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age = "18"
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age_int = int(age)
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print(age_int+2)
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```
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输出：
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```py
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20
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```
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但是你应该记住一些特殊情况：
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1. 浮点（带小数部分的整数）作为参数将返回向下舍入到最接近的整数的浮点数。 例如： `print(int(7.9))`将打印`7` 。 `print(int("7.9"))`也会导致错误，因为字符串是转换为整数的无效参数。
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```py
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Traceback (most recent call last):
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File "<stdin>", line 1, in <module>
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ValueError: invalid literal for int() with base 10: '7.9'
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```
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2. 如果作为参数给出，任何单词中的任何整数都将返回与上面相同的错误： `print(int("one"))`将给出如下错误：
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```py
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Traceback (most recent call last):
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File "<stdin>", line 1, in <module>
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ValueError: invalid literal for int() with base 10: 'one'
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```
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#### 更多信息：
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可在[此处](https://docs.python.org/3.6/library/functions.html#int)找到`int()`内置的官方文档
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