Many languages have the if else conditional selection combination, but there are more places where else is used in python, such as loop for or while, which can be combined with else.
The following is a brief introduction to the for-else while-else combination
When the else in the loop combination is executed, the loop ends normally (that is, it does not exit using break). For example, the following code:
numbers = [1,2,3,4,5] for n in numbers: if (n > 5): print('the value is %d '%(n)) break else: print('the for loop does not end with break') i = 0 while(numbers[i] < 5): print('the index %d value is %d'%(i, numbers[i])) if (numbers[i] < 0) : break i = i + 1 else: print('the loop does not end with break') numbers = [1,2,3,4,5] for n in numbers: if (n > 5): print('the value is %d '%(n)) break else: print('the for loop does not end with break') i = 0 while(numbers[i] < 5): print('the index %d value is %d'%(i, numbers[i])) if (numbers[i] < 0) : break i = i + 1 else: print('the loop does not end with break')
The execution result is as follows:
C:\Python27>python.exe for_else.py the for loop does not end with break the index 0 value is 1 the index 1 value is 2 the index 2 value is 3 the index 3 value is 4 the loop does not end with break
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