TypeError：无法连接'str'和'float'对象

Question

我已经搜索并找不到如何解决这个问题，或者如何解决它。任何帮助表示赞赏，谢谢。

我的代码如下：

def main(): 
temperature = raw_input("Please enter an integer followed by a single space then either a F for Fahrenheit, C for Celsius, K for Kelvin, or R for Rankine: ") 
    # algorithm for Farenheit to Kelvin, Celsius, and Rankine 
    if temperature[-1] == "F": 
    K = (temperature[:-1] + (459.67) * (5.0/9.0)) 
    print K 
    C = (temperature[:-1] - 32) * (5.0/9.0) 
    print C 
    R = (temperature[:-1] + 459.67) 
    print R 
    # algorithm for Celsius to Kelvin, Fahrenheit, and Rankine 
    elif temperature[-1] == "C": 
     K = (temperature[:-1] + 273.15) 
     print K 
     F = (temperature[:-1] * (9.0/5.0) + 32) 
     print F 
     R = (temperature[:-1] + 273.15) * (9.0/5.0) 
     print R 
    # algorithm for Kelvin to Celsius, Fahrenheit, and Rankine 
    elif temperature[-1] == "K": 
     C = (temperature[:-1] - 273.15) 
     print C 
     F = (temperature[:-1] * (9.0/5.0) - 459.67) 
     print F 
     R = (temperature[:-1] * (9.0/5.0)) 
     print R 
    # algorith for Rankine to Fahrenheit, Celsius, and Kelvin 
    elif temperature[-1] == "R": 
     F = (temperature[:-1] - 459.67) 
     print F 
     C = (temperature[:-1] - 491.67) * (5.0/9.0) 
     print C 
     K = (temperature[:-1] * (5.0/9.0)) 
     print K 
main() 

和我的错误消息我进入后“50 F”：

请输入一个整数，其后由单个空间然后或者华氏，C A F为摄氏，K为开尔文，或R为兰金：50°F

Traceback (most recent call last): 
    File "/Users/Minotza/Documents/multi-unit_temperature_converter.py", line 36, in <module> 
    main() 
    File "/Users/Minotza/Documents/multi-unit_temperature_converter.py", line 5, in main 
    K = (temperature[:-1] + (459.67) * (5.0/9.0)) 
TypeError: cannot concatenate 'str' and 'float' objects 
>>> 

Answer 1

raw_input全部更换temperature[:-1]返回用户输入的string。你在找什么是float。在Python中，无法将string和float对象一起添加。所以，你将不得不做的第一个输入转换为float，以便您可以对其执行数学运算。

这是我会怎么做：

user_input = raw_input("Prompt Text...").split(' ') 

temperature = float(user_input[0]) 
units_or_option = user_input[1] 

所以，split方法使一个列表出来什么样的用户输入，使用空格字符分割的条目。 temperature包含前面的第一件东西，铸造成float。 units_of_option包含在数字和空格后输入的字符。

因此，如果用户输入：

123.5 F 

变量的数值：

user_input = ["123.5", "F"] 
temperature = 123.5 
units_or_option = "F" 

Answer 2

temperature = raw_input("Please enter an integer followed by a single space then either a F for Fahrenheit, C for Celsius, K for Kelvin, or R for Rankine: ") 

raw_input返回一个字符串，所以你想分割字符串或将它转换成每一步到一个浮动。

它总是最好设置为变量的数量，而不是重复计算它的，所以你可以做第

将其转换为浮点数：

temperature = raw_input("Please enter an integer followed by a single space then either a F for Fahrenheit, C for Celsius, K for Kelvin, or R for Rankine: ") 
temp = float(temperature.split(' ')[0]) 

返回什么string.split(obj)所做的是string的部分清单，将其与obj分开。例如，如果用户输入273 K，并因此temperature == '273 K',temperature.split(' ')通过在每个空间拆分它创建一个列表，该空间变为['273', 'K']。但是，这些仍然是字符串，所以我们想将第一个转换为浮点数，所以我们做float(temperature.split(' ')[0]) # we only want to convert the first element。

你改进的代码，用temp更换temperature[:-1]与unit更换temperature[-1]（它总是良好的编程习惯，以创建变量，而不是计算值多次）：

def main(): 
    temperature = raw_input("Please enter an integer followed by a single space then either a F for Fahrenheit, C for Celsius, K for Kelvin, or R for Rankine: ") 
    # algorithm for Farenheit to Kelvin, Celsius, and Rankine 
    temp, unit = float(temperature.split(' ')[0]), temperature[-1] # multi-assignment 
    if unit == "F": 
     K = (temp + (459.67) * (5.0/9.0)) 
     print K 
     C = (temp - 32) * (5.0/9.0) 
     print C 
     R = (temperature[:-1] + 459.67) 
     print R 
    # algorithm for Celsius to Kelvin, Fahrenheit, and Rankine 
    elif unit == "C": 
     K = (temp + 273.15) 
     print K 
     F = (temp * (9.0/5.0) + 32) 
     print F 
     R = (temp + 273.15) * (9.0/5.0) 
     print R 
    # algorithm for Kelvin to Celsius, Fahrenheit, and Rankine 
    elif unit == "K": 
     C = (temp - 273.15) 
     print C 
     F = (temp * (9.0/5.0) - 459.67) 
     print F 
     R = (temp * (9.0/5.0)) 
     print R 
    # algorith for Rankine to Fahrenheit, Celsius, and Kelvin 
    elif temperature[-1] == "R": 
     F = (temp - 459.67) 
     print F 
     C = (temp - 491.67) * (5.0/9.0) 
     print C 
     K = (temp * (5.0/9.0)) 
     print K 
main() 

Answer 3

你需要的只是2点的变化：
1：刚raw_input后
添加temperature=float(temperature.split(' ')[0]),temperature.split(' ')[1]为temperature
例如：

temperature = raw_input("Please enter an integer followed by a single space then either a F for Fahrenheit, C for Celsius, K for Kelvin, or R for Rankine: ") 
temperature=float(temperature.split(' ')[0]),temperature.split(' ')[1] 
##. . . . your code 

第二：
与temperature[0]

您的最终代码

def main(): 
    temperature = raw_input("Please enter an integer followed by a single space then either a F for Fahrenheit, C for Celsius, K for Kelvin, or R for Rankine: ") 
    # algorithm for Farenheit to Kelvin, Celsius, and Rankine 
    temperature=float(temperature.split(' ')[0]),temperature.split(' ')[1] 
    if temperature[-1] == "F": 
     K = (temperature[0] + (459.67) * (5.0/9.0)) 
     print K 
     C = (temperature[0] - 32) * (5.0/9.0) 
     print C 
     R = (temperature[0] + 459.67) 
     print R 
    # algorithm for Celsius to Kelvin, Fahrenheit, and Rankine 
    elif temperature[-1] == "C": 
     K = (temperature[0] + 273.15) 
     print K 
     F = (temperature[0] * (9.0/5.0) + 32) 
     print F 
     R = (temperature[0] + 273.15) * (9.0/5.0) 
     print R 
    # algorithm for Kelvin to Celsius, Fahrenheit, and Rankine 
    elif temperature[-1] == "K": 
     C = (temperature[0] - 273.15) 
     print C 
     F = (temperature[0] * (9.0/5.0) - 459.67) 
     print F 
     R = (temperature[0] * (9.0/5.0)) 
     print R 
    # algorith for Rankine to Fahrenheit, Celsius, and Kelvin 
    elif temperature[-1] == "R": 
     F = (temperature[0] - 459.67) 
     print F 
     C = (temperature[0] - 491.67) * (5.0/9.0) 
     print C 
     K = (temperature[0] * (5.0/9.0)) 
     print K 
main()