Parse through textwave to look for specific character

Hello, I'm trying parse through a textwave that has data points containing things like "(4+)", "3+", "(17/2)-", "1(+)", "3/2-" , "(1,2)", etc. What I want to do is check if a data point contains a "+" or a "-" and if it does, put a "+" or a "-" respectively, into a new wave but in the same index as the wave being searched. I.e. if index (data point) 6 contains a "+", put a "+" in index 6 of the new wave. 

I'm running into a problem where any data point that contains a "," , "/" , and "()" it doesn't work. Can someone help explain why StrSearch isnt working for this?

Function test()
    wave/T test_PI
    variable len = numpnts(test_PI)
    variable i
    make/O/T/N=(len) PI_tested
         PI_tested[i] = "+"
            PI_tested[i] = "-"


StrSearch returns the byte offset of the character you are trying to match e.g. "(4+)" would give 2. If you don't care about the position of the character then maybe you need to use StringMatch, or GrepString, or just change ==1 to >-1 i.e.  (StrSearch(test_PI[i],"-",0) >-1) 

Something such as this may be helpful.

Function check_signs()

    wave/T testwave
    wave iwave

    iwave = -GrepString(testwave[p],"-")
    iwave = iwave == 0 ? GrepString(testwave[p],"\+") : iwave
    return 0
make/T/N=6 testwave={"(4+)", "3+", "(17/2)-", "1(+)", "3/2-" , "(1,2)"}
make/N=6 iwave
edit testwave, iwave

(edit -- now sets values for both negative and positive signs)