Python 嵌套循环

Python 编程语言允许在另一个循环中使用一个循环。以下部分用了几个示例来说明这个概念

语法

for iterating_var in sequence:
   for iterating_var in sequence:
      statements(s)
   statements(s)

Python 编程语言中嵌套 while 循环语句的语法如下：

while expression:
   while expression:
      statement(s)
   statement(s)

关于循环嵌套的最后一点是，您可以将任何类型的循环放入任何其他类型的循环内。例如 for 循环可以在 while 循环中，反之亦然。

示例

以下程序使用嵌套的 for 循环来查找从 2 到 100 的素数 -

#!/usr/bin/python

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, " is prime"
   i = i + 1

print "Good bye!"

运行示例

执行上述代码时，会产生以下结果 -

2 is prime
3 is prime
5 is prime
7 is prime
11 is prime
13 is prime
17 is prime
19 is prime
23 is prime
29 is prime
31 is prime
37 is prime
41 is prime
43 is prime
47 is prime
53 is prime
59 is prime
61 is prime
67 is prime
71 is prime
73 is prime
79 is prime
83 is prime
89 is prime
97 is prime
Good bye!