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Python from 0 to 1 (day 13) - Python data application 3

2022-01-31 22:48:34 My family

This is my participation 11 The fourth of the yuegengwen challenge 18 God , Check out the activity details :2021 One last more challenge

int() function

The way to convert data to integer type is also very simple , Namely int() function . Its use method is the same as str() equally , Put the content you need to convert in parentheses , like this :int( Converted content ).

Now let's try , To calculate the number1 and number2 The sum of these two variables .【 The point tip :1. int() Data type conversion function ;2. Operator + Calculation ;3. print() function 】

number1 = '618'

number2 = '1111'

print(int(number1) + int(number2))
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But for the int() Use of functions , We should pay attention to : Only those that conform to the integer specification String class data , Can be int() Coercive transformation .

Although it has only one sentence , But it has three meanings : First , A string of integers, for example '618' and '1111', Can be int() Function cast .

Last , String in decimal form , because Python Grammatical rules , Can't be used int() Function cast .

Let's say the following code , If you click Run , The program will report an error 【ValueError:invalid literal for int() with base 10: '6.18'】( Value anomaly : Floating point type string cannot be used int() Coercive transformation ).


#  Display the results after running :ValueError:invalid literal for int() with base 10: '6.18'
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Does that mean , Floating point number cannot be converted to integer type ?

No , Although floating-point form character string , Out of commission int() function . but Floating point numbers Yes, it can be. int() Function cast .

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The code string above , Is a floating point number 6 .18 Cast statement . however , Why the output is 6 Well ?

You see ,int() The essence of a function is to convert data to integers . So for floating point numbers ,int() The function does rounding . however , It is different from our usual method of rounding decimals ,int() function Will erase directly , Direct output integer part .

Last , Let's summarize int() Knowledge points of function .

But , If this happens : A string is in decimal form , such as '3.8' such . I don't want it to be an integer 3, Want to keep it in decimal form 3.8, What am I going to do ?

This involves our last knowledge point ——float() function .

float() function

First float() Use of functions , Also put the data to be converted in brackets , like this :float( data ).

secondly ,float() The function can also put Integers and character string Convert to floating point type . But at the same time , If the data in brackets is character string type , Then the data must be in digital form .

that , After before str() and int() practice ,float() Function is not easy to understand some ?

below , Let's play a piece of code and practice .

width = 40.0
length = 120.0
weight = "20"
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In the last question ,widht And lenght The variable is already a floating point type ,weight It's a string type ( It can be used type( Variable ) To see the data types ), Therefore, before printing, it will weight Conduct float(weight) Just convert . Up to now , You already know how to convert data types . below , Let's summarize these three functions through a graph .

What about? ? Master the data type 、 You have three knowledge points of data splicing and data conversion , Do you have a sense of achievement to be a big man ?

that , Let's take a look at what you have learned !

But these , It's just the beginning , Later you will learn more complex code and commands , Master more communication skills with computers .

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