#!/usr/bin/env python3
 
n = 100
 
sum = 0
counter = 1
while counter <= n:
  sum = sum + counter
  counter += 1
 
print("1 到 %d 之和为: %d" % (n,sum))

#!/usr/bin/python3
 
var = 1
while var == 1 : # 表达式永远为 true
  num = int(input("输入一个数字 :"))
  print ("你输入的数字是: ", num)
 
print ("Good bye!")

#!/usr/bin/python3
 
count = 0
while count < 5:
  print (count, " 小于 5")
  count = count + 1
else:
  print (count, " 大于或等于 5")

#!/usr/bin/python
 
flag = 1
 
while (flag): print ('欢迎访问编程素材网!')
 
print ("Good bye!")

for <variable> in <sequence>:
  <statements>
else:
  <statements>

>>>languages = ["C", "C++", "Perl", "Python"] 
>>> for x in languages:
...   print (x)
... 
C
C++
Perl
Python
>>>

#!/usr/bin/python3
 
sites = ["Baidu", "Google","jb51","Taobao"]
for site in sites:
  if site == "jb51":
    print("编程素材网!")
    break
  print("循环数据 " + site)
else:
  print("没有循环数据!")
print("完成循环!")

>>>for i in range(5):
...   print(i)
...
0
1
2
3
4

>>>for i in range(5,9) :
  print(i)
 
  
5
6
7
8
>>>

>>>for i in range(0, 10, 3) :
  print(i)
 
  
0
3
6
9
>>>

>>>for i in range(-10, -100, -30) :
  print(i)
 
  
-10
-40
-70
>>>

>>>a = ['Google', 'Baidu', 'Runoob', 'Taobao', 'QQ']
>>> for i in range(len(a)):
...   print(i, a[i])
... 
0 Google
1 Baidu
2 Runoob
3 Taobao
4 QQ
>>>

>>>list(range(5))
[0, 1, 2, 3, 4]
>>>

#!/usr/bin/python3
 
for letter in 'Jb51net':   # 第一个实例
  if letter == 'e':
   break
  print ('当前字母为 :', letter)
 
var = 10          # 第二个实例
while var > 0:       
  print ('当期变量值为 :', var)
  var = var -1
  if var == 5:
   break
 
print ("Good bye!")

#!/usr/bin/python3
 
for letter in 'Jb51net':   # 第一个实例
  if letter == 'n':    # 字母为 o 时跳过输出
   continue
  print ('当前字母 :', letter)
 
var = 10          # 第二个实例
while var > 0:       
  var = var -1
  if var == 5:       # 变量为 5 时跳过输出
   continue
  print ('当前变量值 :', var)
print ("Good bye!")

#!/usr/bin/python3
 
for n in range(2, 10):
  for x in range(2, n):
    if n % x == 0:
      print(n, '等于', x, '*', n//x)
      break
  else:
    # 循环中没有找到元素
    print(n, ' 是质数')

>>>while True:
...   pass # 等待键盘中断 (Ctrl+C)

>>>class MyEmptyClass:
...   pass

#!/usr/bin/python3
 
for letter in 'Jb51net': 
  if letter == 'n':
   pass
   print ('执行 pass 块')
  print ('当前字母 :', letter)
 
print ("Good bye!")

>>> sequence = [12, 34, 34, 23, 45, 76, 89]
>>> for i, j in enumerate(sequence):
...   print(i, j)
... 
0 12
1 34
2 34
3 23
4 45
5 76
6 89

#!/usr/bin/env python3

n = 0
sum = 0
for n in range(0,101):# n 范围 0-100
  sum += n
print(sum)

#!/usr/bin/python3

#外边一层循环控制行数
#i是行数
i=1
while i<=9:
   #里面一层循环控制每一行中的列数
   j=1
   while j<=i:
     mut =j*i
     print("%d*%d=%d"%(j,i,mut), end=" ")
     j+=1
   print("")
   i+=1

#!/usr/bin/python3

for i in range(1,6):
  for j in range(1, i+1):
   print("*",end='')
  print('\r')