Question

我目前正在阅读本书： Introduction to Computation and Programming Using Python。

我目前正在处理的问题是：

设s是一个包含由逗号分隔的十进制数字序列的字符串，例如s = '1.23,2.4,3.123'。编写一个程序，打印s中的数字总和。

我已经想出了整数的方法：

s = raw_input('Enter any positive integers: ')

total = 0

for c in s:

    c = int(c)

    total += c

print total

我尝试了几种方法，包括try和except方法，但我可以弄清楚如何解决

Valuerror:invalid literal for int() with base 10: '.'

我感谢任何帮助。谢谢。

更新：我要感谢每个人的帮助。很高兴知道有人愿意帮助小乔。

Answer 1

sum(map(float,raw_input("Enter any positive integers: ").split(',')))

这是一种快速而肮脏的单线作为快速黑客攻击。这里展开了一点：

input_string = raw_input("Enter any positive integers: ")
#input_string is now whatever the user inputs

list_of_floats_as_strings = input_string.split(",")
#this splits the input up across commas and puts a list in
#list_of_floats_as_strings. They're still strings here, not floats yet,
#but we'll fix that in a moment

running_total = 0 #gotta start somewhere

for value in list_of_floats_as_strings:
    number = float(value) #turn it into a float
    running_total+=number #and add it to your running total

#after your for loop finishes, running_total will be the sum you're looking for

关于快速脏单线的确切做法：

sum( #tells Python to add up everything inside the brackets
    map( #tells Python to run the designated function on everything in the
         #iterable (e.g. list or etc) that follows
        float, #is the float() function we used in the unrolled version
        raw_input("Enter any positive integers: ") #is your input
            .split(',') #splits your input into a list for use in map
        )
    )

请不要像我刚才那样编写代码。将那些脏的单行保持为脏的单行，并在之后解释它们。我认为这种格式对于一次性解释可能更好，但是对于文档而言，它确实更糟糕。

Answer 2

使用split和float，例如

s = raw_input('Enter any floats: ')
print s

items = s.split(",")
print "items:",items

floats = map(float, items)
print "floats:",floats

total = sum(floats)
print "total:",total

输出为

Enter any floats: 12.3,45.6,78.9
12.3,45.6,78.9
items: ['12.3', '45.6', '78.9']
floats: [12.3, 45.6, 78.9]
total: 136.8

Answer 3

这是使用for循环的解决方案。

# Save the string (e.g. '12.5,67.4,78.5')
number_string = raw_input("Enter any positive floats: ")

# Initialize a variable to hold the sum of the numbers
tot = 0

# Iterate over all numbers in the string. The string is splitted 
# at each comma, thus resulting in a list like `['12.5', '67.4', '78.5']`
for num in number_string.split(','):
    # But every element in the list is a string, so you need to 
    # convert them to floats, and add each of them to the total sum
    tot += float(num)

# Print the total sum
print tot

正如其他人所指出的那样，通过编写更少的代码，您可以更轻松地完成此任务，但这可能更容易理解。当您理解这一点时，您可能会理解其他解决方案的工作原理。

在python 2.7中从字符串中提取多个浮点

3 个答案: