不会将字符串格式的十进制数字转换为浮点数

Question

I have a problem with my code and I just don't understand why its not working. The code:

total = 0
with open("receipt.txt", "r") as receipt:
    for line in receipt:
        the_line = line.split(",")
        total_product = the_line[4]
        total_product = total_product.translate(None, '\n')
        print total_product
        total += float(total_product)

with open("receipt.txt", "a") as receipt:
    receipt.write("Total of Items:            " + total)

The total_product when printed to console is:

5.94
807.92
2000.40
0.00

What I don't understand is why its not converting each of those to floats and instead prints error to console:

TypeError: cannot concatenate 'str' and 'float' objects

I would love it if someone could tell me how to fix it or/and why its doing it.

Answer 1

Your code actually is successfully converting each of the total_product s to a float. The error is in the last line of your snippet where you try to concatenate your string output with the value of your total variable (which is still a float). You should use either string formatting (recommended solution):

with open("receipt.txt", "a") as receipt:
    receipt.write("Total of Items:            {:.2f}".format(total))

or just cast your float to a string:

with open("receipt.txt", "a") as receipt:
    receipt.write("Total of Items:            " + str(total))

Answer 2

Convert the total variable which is type float to a string

receipt.write("Total of Items:            " + str(total))

Here is an example:

total = 13.54
str(total)
>> '13.54'