using indexOf() and substring().

Projects Programming
1

i would like to capture the value of a text box submitted from a form. My URL when the form is submitted is:

http://192.168.0.25/?startTime=33&duration=

GET /?startTime=33&duration= HTTP/1.1
Host: 192.168.0.25
Connection: keep-alive
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,/;q=0.8
User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_9_3) AppleWebKit/537.75.14 (KHTML, like Gecko) Version/7.0.3 Safari/537.75.14
Accept-Language: en-us
Referer: http://192.168.0.25/?startTime=&duration=
Accept-Encoding: gzip, deflate

start time is=33&duration=

I need to set the variable startTime to 33.

I have the index of “startTime” in the URL. I can get what comes after “startTime” in the URL but I am getting everything that comes after it, not just the two number. (33).

My code is:

                        int stTimeInd = HTTP_req.indexOf("startTime=");
                      
                    
                        String startTime = HTTP_req.substring(stTimeInd+9);  ////////////   this is where i need the help (I think)
                        Serial.print("start time is");
                        Serial.println(startTime);

I commented the line where i think i am in trouble.

2

If indexOf() successfully returns the location of the =, why does it not successfully return the location of the &?

Or perhaps I should ask why you aren't asking for the location of the &. The substring of interest is between the = and the &, isn't it?

3

Im not sure what you are asking me. I am looking for the location of "startTime=" and what i want to capture is everything between "startTime=" and "&". So in other words using the example i gave in my original post, When i submit the form (URL: http://192.168.0.25/?startTime=33&duration=) the result of "Serial.println(startTime)" needs to be"start time is=33. What i am getting is :start time is=33&duration=

The line where i think i have the issue is:

String startTime = HTTP_req.substring(stTimeInd+9);

This is requesting a string starting at the 9th position after startTime=, what i need to find out is how to tell it where to stop. I want to limit what it returns to what is between "startTime=" and the ampersand.

Even if i could limit what it returns to 2 characters that would be fine as well since this will always be a two digit number.

4

I think the general approach would be to split the URL at the first '?' to find the start of the URL-encoded values, and then split the right hand side at '&' to separate the value assignments, and then split each assignment at '=' to separate the name from the value. If your URL can include entity references then the decoding would need to be a bit cleverer. This feels like the sort of common requirement that somebody somewhere will surely have implemented as a library.

If you only want to deal with this specific value then you could search for "startTime=" and the following '&' and anything in between them should be the value you want.

5

That is correct. The issue i have is how do i do it? What is the code i need to limit the string to what is between startTime= and the ampersand? I can get everything after startTime=, but how do i stop it at the ampersand?

6

Find the position of the ampersand. The string you want ends at the preceding character. You have already found where the string starts.

7

Im not sure what you are asking me. I am looking for the location of "startTime=" and what i want to capture is everything between "startTime=" and "&".

No, the string you want to capture is between the = and the &. You need to find the location of startTIme= ONLY so that you know that the substring between the = and the & IS the start time.

Once you know that indexOf("startTime=") is not -1, the the actual value does NOT matter.

Get the indexOf() the =. Get the indexOf() the &. The stubstring starts at indexOf("=")+. The length is indexOf("&") - indexOf("=) - 1.

8

NOW I GOT IT!!!!

Thanks for the help.

9

hi can u please send the code of the instruction because i have the same problem

+IPD,0,121:GET /?|Bonjour$ HTTP/1.1
Host: 192.168.1.30
Connection: Keep-Alive
Accept-Encoding: gzip
User-Agent: okhttp/3.0.1

i want to extract bonjour thank you .

10

hello Houssem99 .. i have the same issue.
would u please give me a clear line of indexof() .. so i capture my missing word from the http line?
thank you