如何在 Python 中舍入为整数？

Question

I have an assignment and am having a bit of trouble with it.

Here is my question:

Write a program that asks the user for the number of males and the number of females registered in a class using two separate inputs ("Enter number of males:", "Enter number of females:").
The program should display the percentage of males and females (round to the nearest whole number) in the following format:

Percent males: 35%
Percent females: 65%

Use string formatting.

My issue is that I am not able to round the percent of males and females. For example, the program I am using to grade the code input had 150 males and 250 females. My program got the percentage of 37% males instead of 38%.

Here is my code that I have now

number_of_males = int(input("Enter number of males:"))
number_of_females = int(input("Enter number of females:"))
    
total = (number_of_males + number_of_females)
    
percentage_male = ((number_of_males/total)*100)
percentage_female = ((number_of_females/total)*100)
    
print("Percent males: " + str( int(percentage_male )) + '%')   
print("Percent females: " + str( int(percentage_female )) + '%')

So far I have tried this, but it is giving me an error. I am probably typing the round function out incorrectly.

line 9, in <module>
    print("Percent males: " + str( (round(int(percentage_male ))) + '%'))
TypeError: unsupported operand type(s) for +: 'int' and 'str'

number_of_males = int(input("Enter number of males:"))
number_of_females = int(input("Enter number of females:"))
    
total = (number_of_males + number_of_females)
    
percentage_male = ((number_of_males/total)*100)
percentage_female = ((number_of_females/total)*100)
    
print("Percent males: " + str( (round(int(percentage_male ))) + '%')) 
print("Percent females: " + str( int(percentage_female )) + '%')

Answer 1

Yes, as you have guessed you are trying to round up a number which is already an integer.

for example: int(10.6) returns the truncated integer part of the number '10.6'. which returns 10 in this case.

so if we use round(int(10.6)) what happens is, we're just trying to round up 10 . which is similar to round(10) .

instead what you wanna do is round(10.6) which returns an 11.

additionally, there are some extra parentheses used in line9 which causes the type error.

in your scenario,

number_of_males = int(input("Enter number of males:"))
number_of_females = int(input("Enter number of females:"))

total = (number_of_males + number_of_females)

percentage_male = ((number_of_males/total)*100)
percentage_female = ((number_of_females/total)*100)

print("Percent males: " + str(round(percentage_male)) + '%')

print("Percent females: " + str(round(percentage_female)) + '%')

will do the job.

furthermore, you can rearrange the code by removing unnecessary parentheses.

number_of_males = int(input("Enter number of males:")) 
number_of_females = int(input("Enter number of females:"))

total = number_of_males + number_of_females

percentage_male = number_of_males/total*100 
percentage_female = number_of_females/total*100

print("Percent males: " + str(round(percentage_male)) + '%')
print("Percent females: " + str(round(percentage_female)) + '%')

Answer 2

You can't add a number and the string '%' . You can fix it with

print("Percent males: " + str( (round(int(percentage_male )))) + '%')

But you also don't need the int function. It makes no sense to round an integer. int removes the decimal part (round towards zero). You should skip it:

print("Percent males: " + str(round(percentage_male)) + '%')

and get the same result.

number_of_males = int(input("Enter number of males:"))
number_of_females = int(input("Enter number of females:"))

total = number_of_males + number_of_females

percentage_male = number_of_males / total * 100
percentage_female = number_of_females / total * 100

print("Percent males: {}%".format(round(percentage_male)))

print("Percent females: {}%".format(round(percentage_female)))

Answer 3

Python has builtin formatting which include formatting as a presentage, for example:

>>> p = 0.45
>>> format(p, '.0%')
'45%'
>>> f"{p:.0%}"
'45%'

so in your case it would be:

percentage_male = number_of_males / total
percentage_female = number_of_females / total

print(f"Percent males: {percentage_male:.0%}")

print(f"Percent females: {percentage_female:.0%}")