how do you test an expression without it running?-CodePudding

Is there a way to test if an expression leads to an error without running it normally (which would lead to a program crash)? In particular, the chunk int(temp[1]) without knowing whether or not temp[1] is a number (as in a string number such as "10" or "142")? The reason I'm trying to do this is to implement error handling involving in regards to user input.

CodePudding user response：

You can use type(temp[1]) or isinstance(temp[1], int) to check types. To specifically check if strings are numbers, use temp[1].isdigit().

CodePudding user response：

You could try if isinstance(temp[1], int). This checks if temp[1] is an instance of the int class.

Another way to do this is to catch the error itself. That way you know for a fact that it causes the error. For example:

try:
    int(temp[1])
except ValueError:
    print("The variable temp[1] can't be changed to an int.")