NameError: 名称 'rindex' 未定义

Question

I get this error when calling my python script from command line, passing in an input string (parameter 1) and a blank string (parameter 2) that will store my output from parsing this input string in my module

C:\Windows\system32>set project_name=

C:\Windows\system32>echo "%project_name%" " "

C:\Windows\system32>"C:\Python27\python" "C:\IR125422\GetProject1.py" "#p=/Product Delivery/Product Delivery.pj#s=Team P rojects/Team Projects.pj#s=Platform Pack/Platform Pack.pj#s=Runtime/Runtime.pj"   project_name

Traceback (most recent call last):   File "C:\IR125422\GetProject1.py", line 5, in <module>
    startpos = rindex("/",stext) NameError: name 'rindex' is not defined

My python program takes the string staring with "#p" and locates the last substring "/" in the string, then copies into the string project_name the remainder of this string from the last "/" to the end of the string. So after the program is run project_mane should contain "runtime.pj"

Here is the program

import os, sys
stext = sys.argv[1]
rtext =  sys.argv[2]
startpos = rindex("/",stext)
rtext = stext(startpos+1,len(rtext))
print "Extracting project"
print rtext;

However it seems that the string method rindex is not recognised. Do I need to add a module to my "Import" section? I thought that this was not required for string handling in python as it is intrinsic to python

Answer 1

rindex is not available as a global function, but rather as a method of the str class. The usage is str.index(self, sub[, start[, end]]) . So if you replace the line:

startpos = rindex("/",stext)

with either of the following two:

startpos = str.rindex(stext, "/")
startpos = stext.rindex("/")

the line in question should work.

Note however that the following line also contains an error:

rtext = stext(startpos+1,len(rtext))

As it is currently, you would be calling stext as if it were a function, rather than indexing it as an iterable. Try the following instead:

rtext = stext[startpos+1:]

This will result in a " slice " of the original string, starting at startpos+1 and ending at the end of the string. So your complete code, without further modification would be:

import os, sys
stext = sys.argv[1]
rtext =  sys.argv[2]
startpos = stext.rindex("/") # This line changed
rtext = stext[startpos+1:]   # This line changed
print "Extracting project"
print rtext;

Giving the output:

Extracting project
Runtime.pj

Edited to add:

As suggested by Two-Bit Alchemist, your code can also be cleaned up a bit. The initial assignment to rtext does nothing and can be omitted. The print statements can be combined by adding a newline inside the string and using format , or if you want to somehow capture and use the output in DOS or PowerShell you might even want to omit the first print statement altogether. This may also be a good moment to make the print statements Python3-friendly by adding parentheses. Additionally, Two-Bit Alchemist suggested to calculate rtext more directly:

rtext = stext.split('/')[-1]

Which splits the string into a list at each '/' and then takes the last element, corresponding to the string portion after the final '/' just like the current solution. Finally, the os import is unused and the semicolon after the second print statement is superfluous, therefore both can be omitted. The cleaned up code would be:

import sys
stext = sys.argv[1]
rtext = stext.split('/')[-1]
print(rtext)

Or even more compact:

import sys
print(sys.argv[1].split('/')[-1])