Python `break`语句

break 是 python 中的一个关键字，用于将程序控制带出循环。break语句逐个中断循环，即在嵌套循环的情况下，它首先中断内部循环，然后继续到外部循环。换句话说，我们可以说 break 用于中止程序的当前执行，控制转到循环后的下一行。

中断通常用于我们需要为给定条件中断循环的情况。

中断的语法如下。

#loop statements
break;

例 1

list =[1,2,3,4]
count = 1;
for i in list:
    if i == 4:
        print("item matched")
        count = count + 1;
        break
print("found at",count,"location");

输出:

item matched
found at 2 location

例 2

str = "python"
for i in str:
    if i == 'o':
        break
    print(i);

输出:

p
y
t
h

示例 3:使用 `While`循环`break`语句

i = 0;
while 1:
    print(i," ",end=""),
    i=i+1;
    if i == 10:
        break;
print("came out of while loop");

输出:

0  1  2  3  4  5  6  7  8  9  came out of while loop

例 3

n=2
while 1:
    i=1;
    while i<=10:
        print("%d X %d = %d\n"%(n,i,n*i));
        i = i+1;
    choice = int(input("Do you want to continue printing the table, press 0 for no?"))
    if choice == 0:
        break;    
    n=n+1

输出:

2 X 1 = 2

2 X 2 = 4

2 X 3 = 6

2 X 4 = 8

2 X 5 = 10

2 X 6 = 12

2 X 7 = 14

2 X 8 = 16

2 X 9 = 18

2 X 10 = 20

Do you want to continue printing the table, press 0 for no?1

3 X 1 = 3

3 X 2 = 6

3 X 3 = 9

3 X 4 = 12

3 X 5 = 15

3 X 6 = 18

3 X 7 = 21

3 X 8 = 24

3 X 9 = 27

3 X 10 = 30

Do you want to continue printing the table, press 0 for no?0