如何解决预期的缩进块错误？

Question

我试图在Python中创建一个BMI计算器，但是当我运行该程序时，它说：'IndentationError：预计一个缩进块'。它说错误在第7行，但是我错了什么？我使用Python 3.5.1

print ('Give your weight in kg: ') 
weight_kg = float(raw_input()) 
print ('Give your length in meters: ') 
length_meters = float(raw_input()) 
bmi = weight_kg/(length_meters * length_meters) 
if bmi <= 18.5: 
print ('Your BMI is'), bmi, ('what means that you have got underweight') 
elif bmi > 18.5 and bmi <= 25: 
print ('Your BMI is'), bmi, ('what means that you have got a normal weight') 
elif bmi > 25 and bmi < 30: 
print ('Your BMI is'), bmi, 'what means that you have got overweight') 
elif bmi >= 30: 
print ('Your BMI is'), bmi, ('what means that you have got obese') 

Answer 1

在Python，下属陈述是指缩进级别进行标识，而相比之下，花括号或开始/其他一些语言使用的一端关键字。因此，Python中的适当缩进不仅仅是风格惯例，而且事实上正确的功能也是必需的。在你的情况下，你需要缩进你的从属陈述。请尝试以下操作：

print ('Give your weight in kg: ') 
weight_kg = float(input()) 
print ('Give your length in meters: ') 
length_meters = float(input()) 
bmi = weight_kg/(length_meters * length_meters) 
if bmi <= 18.5: 
    print ('Your BMI is', bmi, 'what means that you have got underweight') 
elif bmi > 18.5 and bmi <= 25: 
    print ('Your BMI is', bmi, 'what means that you have got a normal weight') 
elif bmi > 25 and bmi < 30: 
    print ('Your BMI is', bmi, 'what means that you have got overweight') 
elif bmi >= 30: 
    print ('Your BMI is', bmi, 'what means that you have got obese')