py必备基础知识

1、如何识别字符数字以及空格

用到string库中的三个判断函数isalpha,isdigit,isspace

import string

s = input(‘请输入一列字符’)

a = 0

b = 0

c = 0

d = 0

for i in s:

if i.isalpha():

a +=1

if i.isspace():

b +=1

if i.isdigit():

c +=1

else:

d +=1

print(‘字母是%d,空格是%d,数字是%d,其他字符是%d’%(a,b,c,d))

2、如何使用字符串

s = ‘星期一星期二星期三星期四星期五星期六星期日’

a = int(input(‘请输入一个数字’))

pos = (a-1)*3

print(s[pos:pos+3])

3、mcmc时π的计算

from random import random

from math import sqrt

from time import clock

DARTS =1200

hits = 0

clock()

for i in range(1,DARTS):

x,y = random(),random()

dist = sqrt(x**2 + y**2)

if dist <= 1.0:

hits = hits + 1

pi = 4 *(hits/DARTS)

print(‘pi的时间%s’%pi)

print(‘程序运行时间是%’%clock())