Python fifth day, two knowledge points three mesh operator and assert throw exception handling.

There were no trinocular operators before Python 2.5x, but with the development of language, three mesh operators were added after 2.5

1 " "2 here the main three-mesh operator3 It is also possible to quickly declare variables and assign values to variables by x,y=4,5 this way. 4 " "5x,y=4,56 ifx<y:7Small=x8 Else:9Small=yTen Print(small) One  A  - Print("after the-----is changed to the three mesh operator----")     -Small=xifX<yElsey the Print(small)

Sometimes we in the development process, the program will be running when the possibility of a false pre-judgment, then we use what method to pre-judgment, this time we use the Assert this function, its role is, when the pre-judgment after the establishment, then run, if not, throw an exception.

　　

1 " " 2 simple usage of assert 3 " " 4 a,b=3,65assert a>b6print(" performed ")

We judge A>b after the assert, but we can see by the assignment that it is not true, and this time the assert throws an exception:

Traceback (most recent):   " e:/python/day-1/three mesh. PY "  in <module>    b=3.6Typeerror:cannot Unpack non-iterable Float Object

But if the conditions in the assert change to B>a, then the program prints "executed."

　

Python fifth day, two knowledge points three mesh operator and assert throw exception handling.