- 定义函数：通过
def关键字定义函数，def的字符串为函数名。 - 函数名括号内用逗号相隔的字符为参数。参数一般设定为必选参数，还可设定为位置参数、默认参数、可变参数、关键字参数等，具体可参见第二条资料。
- 函数主体即缩进的内容。
- 通过
return关键字将函数的数据反馈给调用函数。
以下是两道编程题。
# PAT中的基础编程题目集函数题7-13
def isShadow(Open, High, Low, Close): # 判断阴影类型
if Low < Open and Low < Close and High > Open and High > Close:
return ' with Lower Shadow and Upper Shadow'
elif Low < Open and Low < Close:
return ' with Lower Shadow'
elif High > Open and High > Close:
return ' with Upper Shadow'
else :
return ''
Open, High, Low, Close = input().split(' ')
if float(Open) > float(Close):
print('BW-Solid' + isShadow(float(Open), float(High), float(Low), float(Close)))
elif float(Open) < float(Close):
print('R-Hollow' + isShadow(float(Open), float(High), float(Low), float(Close)))
else :
print('R-Cross' + isShadow(float(Open), float(High), float(Low), float(Close)))
以上程序中，涉及逻辑运算[3]。python3中的逻辑运算并不向C语言中的一样借助于符号。python3中的与通过and实现，或通过or实现，非通过not实现。
以下是通过循环不断缩小区间从而实现二分法求根。
# PAT中的基础编程题目集函数题7-18
def f(x, coeff): # 定义多项式函数
return ((coeff[0] * x + coeff[1]) * x + coeff[2]) * x + coeff[3]
coeff = input().split()
range = input().split() # 此处的range为变量
coeff[0] = float(coeff[0]); coeff[1] = float(coeff[1]); coeff[2] = float(coeff[2]); coeff[3] = float(coeff[3])
a = float(range[0]); b = float(range[1])
if f(a, coeff) == 0: # 考虑结果为断点的情况
b = a
elif f(b, coeff) == 0:
a = b
mid = (a + b) / 2
while f(mid, coeff) != 0 and b - a > 0.001: # 判断循环结束条件
if f(a, coeff) * f(mid, coeff) < 0:
b = mid
elif f(mid, coeff) * f(b, coeff) < 0:
a = mid
mid = (a + b) / 2
print('%.2f' %(mid))
