条件语句
# -*- coding: UTF-8 -*- | |
# 条件语句:例 1:if 基本用法 | |
flag = False | |
name = 'Bob' | |
if name == 'python': # 判断变量否为 'python' | |
flag = True # 条件成立时设置标志为真 | |
print 'welcome boss' # 并输出欢迎信息 | |
else: | |
print name # 条件不成立时输出变量名称 | |
print("\n") | |
# 例 2:elif 用法 | |
num = 5 | |
if num == 3: # 判断 num 的值 | |
print 'boss' | |
elif num == 2: | |
print 'user' | |
elif num == 1: | |
print 'worker' | |
elif num < 0: # 值小于零时输出 | |
print 'error' | |
else: | |
print 'a' # 条件均不成立时输出 | |
print("\n") | |
# 例 3:if 语句多个条件 | |
num = 9 | |
if 0 <= num <= 10: # 判断值是否在 0~10 之间 | |
print 'hello' | |
num = 10 | |
if num < 0 or num > 10: # 判断值是否在小于 0 或大于 10 | |
print 'hello' | |
else: | |
print 'undefined' | |
num = 8 | |
if (0<= num <= 5) or (10<= num <= 15): # 判断值是否在 0~5 或者 10~15 之间 | |
print 'hello' | |
else: | |
print 'undefined' | |
print("\n") | |
# 可以在同一行的位置上使用 if 条件判断语句 | |
var = 100 | |
if var == 100: | |
print "变量 var 的值为100" | |
print "Good bye!" |
循环语句
# -*- coding: UTF-8 -*- | |
# 循环语句:while,break & continue,无限循环 | |
count = 0 | |
while count < 9: | |
print 'The count is:', count | |
count = count + 1 | |
print "--------------------" | |
i = 1 | |
while i < 10: | |
i += 1 | |
if i % 2 > 0: # 非双数时跳过输出 | |
continue | |
print i # 输出双数 2、4、6、8、10 | |
print "--------------------" | |
i = 1 | |
while 1: # 循环条件为 1 必定成立 | |
print i # 输出 1~10 | |
i += 1 | |
if i > 10: # 当 i 大于 10 时跳出循环 | |
break | |
print "--------------------" | |
var = 1 | |
while var == 2: # 如果 var==1,则该条件永远为 true,循环将无限执行下去 | |
num = raw_input("Enter a number :") | |
print "You entered: ", num | |
print "--------------------" | |
count = 0 | |
while count < 5: | |
print count, " is less than 5" | |
count = count + 1 | |
else: | |
print count, " is not less than 5" | |
print "--------------------" | |
flag = 0 # 如果 flag 为 1,则无限循环打印 | |
while flag: | |
print 'Given flag is really true!' | |
print "--------------------" | |
# 输出 Python 的每个字母 | |
for letter in 'Python': | |
if letter == 'h': | |
pass | |
print '这是 pass 块' | |
print '当前字母 :', letter | |
print "Good bye!" |
for 语句
# -*- coding: UTF-8 -*- | |
# 字符串遍历 | |
for letter in 'Python': | |
print '当前字母 :', letter | |
print "--------------------" | |
# 列表遍历 | |
fruits = ['banana', 'apple', 'mango'] | |
for fruit in fruits: # foreach | |
print '当前水果 :', fruit | |
for index in range(len(fruits)): # 通过索引遍历 | |
print '当前水果 :', fruits[index] | |
print "--------------------" | |
# for … else | |
for num in range(10,20): # 迭代 10 到 20 之间的数字 | |
for i in range(2,num): # 根据因子迭代 | |
if num % i == 0: # 确定第一个因子 | |
j=num/i # 计算第二个因子 | |
print '%d 等于 %d * %d' % (num,i,j) | |
break # 跳出当前循环 | |
else: # 循环的 else 部分 | |
print num, '是一个质数' |
嵌套语句
# -*- coding: UTF-8 -*- | |
# while 循环嵌套:输出 2~100 之间的素数 | |
i = 2 | |
while i < 100: | |
j = 2 | |
while j <= (i / j): | |
if not (i % j): break | |
j = j + 1 | |
if j > i / j: print i, " 是素数" | |
i = i + 1 | |
print "---------------------" | |
# for 循环嵌套: | |
listVal = ["kite","bob","john"] | |
for name in listVal: | |
for letter in name: | |
print(letter) |