习题21

def add(a,b):print "ADDING %d+%d"%(a,b)return a+bdef subtract(a,b):print" SUBTRACTING %d-%d"%(a,b)return a-bdef multiply(a,b):print"MUTIPLYING %d*%d"%(a,b)return a*bdef divide(a,b):print"DIVIDING%d/ %d" %(a,b)return a/bprint" Let's do some math with just functions!"age=add(30,5)height=subtract(78,4)weight=multiply(90,2)iq=divide(100,2)print "Age:%d,Height:%d,Weight:%d,Iq:%d"%(age,height,weight,iq)print "Here is a puzzle."what=add(age,subtract(height,multiply(weight,divide(iq,2))))print "That becomes:",what,"Can you do it by hand?"

本节习题的主要内容是return函数的使用，还有将复杂算式作为参数，其中有值，有函数，一层层嵌套，只需从最里面一层慢慢往外解就可以啦。要注意的是单词拼写要慢点。