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char2num or str2num

Wed, 05/25/2011 - 10:35 am

Hi every one, i have a simple question about converting ascii to number. Here, I have some VB program that convert Ascii character (I think) to number:

ibrd ud, recvbuffer, 4
lsb2& = Asc(Left(recvbuffer, 1))
lsb1& = Asc(Right(Left(recvbuffer, 2), 1))
msb2& = Asc(Right(Left(recvbuffer, 3), 1))
msb1& = Asc(Right(Left(recvbuffer, 4), 1))

In Igor, how it should be write?
like this:

NI4882 ibrd={ud,4}

recvbuffer=S_value

lsb1=char2num (Rdbuffer[0])

lsb2=char2num (Rdbuffer[1])

msb1=char2num (Rdbuffer[2])

msb2=char2num (Rdbuffer[3])

NI4882 ibrd={ud,4}

recvbuffer=S_value

lsb1=str2num (Rdbuffer[0])

lsb2=str2num (Rdbuffer[1])

msb1=str2num (Rdbuffer[2])

msb2=str2num (Rdbuffer[3])

When I tried to print the values by using str2num or num2char I just got 'NaN' for each of the value instead of '0'

hrodstein

You are not assigning anything to Rdbuffers. That's why you're getting NaNs. You could discover this by putting:

Print Rdbuffers

in your function or by using the Igor debugger:

DisplayHelpTopic "The Debugger"

char2num returns the numeric code for a single character. str2num converts a string containing text formatted as a number to a numeric value. My guess is that you want the numeric value of a single byte. For that you should use char2num.

I don't think this your situation, but, if S_value contains a number in ASCII format, you can do this:

Variable val = str2num(S_value)

May 25, 2011 at 01:05 pm - Permalink

randomz_raf

There is a mistake in my program. I forgot to change the Rdbuffer to recvbuffer. The actual program is suppose to be like this:

NI4882 ibrd={ud,4}

recvbuffer=S_value

lsb1=char2num (recvbuffer[0])

lsb2=char2num (recvbuffer[1])

msb1=char2num (recvbuffer[2])

msb2=char2num (recvbuffer[3])

May 30, 2011 at 05:19 am - Permalink