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This article is a detailed introduction to "what is the difference between format function and round function in python". The content is detailed, the steps are clear, and the details are properly handled. I hope this article "what is the difference between format function and round function in python" can help you solve your doubts. Let's go deeper and learn new knowledge together with the ideas of Xiaobian.

the difference

Different return types: format function returns str string after formatting, round function returns float

Different carry: When several decimal places are reserved, format follows the rounding principle, while round does not follow this principle. The round carry principle is rounded and even.

The number of digits reserved is different: if the 6 decimal places are reserved, the format function outputs the result with 6 decimal places reserved after the decimal point, while the round function is slightly flexible, and it will remove the decimal places ending with 0, that is, retain the non-zero part.

Functions are different: round function mainly acts on floating-point data to retain a number of decimals, format function can not only retain a number of decimals, its main function is to format strings, custom output strings.

round function carry principle

What is rounding sub-coupling? Look at the last digit, if the last digit is less than or equal to 4, then drop it, if the last digit is greater than or equal to 6, then enter one digit; if the last digit is 5, it is necessary to discuss the situation: if the penultimate digit is even, enter one digit, and if it is odd, drop it.

Example>>> round (2.674,2) #If the parameter is 2, keep two decimal places, look at the third decimal place, if it is less than or equal to 4, then drop 2.67>> round (2.645,2) #= 5, then look at the penultimate digit, 4 is even, sub-even, then enter one digit 2.65>> round (2.655,2)#5 is odd, sub-even, so drop 2.65>>> round (2.675,2)2.67>>> round (2.685,2)2.69>>> round (2.695,2)2.69>> round(2.676,2) #The third decimal place is greater than or equal to 6, so enter one digit 2.68>> type(round(2.674,2)) #The result is floating point type>>> round(3.677,6) #When the specified decimal places exceed the actual number of decimal places, only the non-zero part is retained 3.677format function

Format function is powerful, writing format is various, we combine examples to explain the operation process.

Example>>> format ('2.674','.2f') #When using this method to reserve decimals, the first argument must not be a string type Traceback (most recent call last): File "", line 1, in format ('2.674','.2f') ValueError: Unknown format code 'f' for object of type 'str'>> format ('2.674','.2f')#Correct format '.2f' means to retain two decimal places '2.67'>>> format (3.677,'.6f')#Specify how many decimal places to keep will keep a few decimal places'3.677000'>>> print ("lishuaige is %.3f ah" % 6.66555) #fixed-point digital format output lishuaige is 6.666 ah>> print ("lishuaige is {:.3f} ah".format(6.66555))lishuaige is 6.666 ah read here, this article "python format function and round function what is the difference" article has been introduced, want to master the knowledge points of this article also need to practice to understand, if you want to know more about the content of the article, welcome to pay attention to the industry information channel.

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