从字符串到整数的转换

Question

I'm communicating with a modem via COM port to recieve CSQ values.

response = ser.readline()
csq = response[6:8]

print type(csq)

returns the following:

<type 'str'> and csq is a string with a value from 10-20

For further calculation I try to convert "csq" into an integer, but

i=int(csq)

returns following error:

invalid literal for int() with base 10: ''

Answer 1

一种稍微更Python化的方式：

i = int(csq) if csq else None

Answer 2

Your error message shows that you are trying to convert an empty string into an int which would cause problems.

Wrap your code in an if statement to check for empty strings:

if csq:
    i = int(csq)
else:
    i = None

Note that empty objects (empty lists, tuples, sets, strings etc) evaluate to False in Python.

Answer 3

As alternative you can put your code inside an try-except-block:

try:
    i = int(csq)
except:
    # some magic e.g.
    i = False