Finding previously defined string in input file

[SumTingWong59]

So basically we'll just say that, for example, the user inputs 'As' and it is set to variable 'A'.
I have an input .txt file that has a list of these characters (it's for figuring out molecular geometry) so somewhere in the text file it says
'Arsenic As 5'
I want to have my program run through the input file, looking for the contents of string 'A,' retrieve the 5, and assign it to another variable, 'v.' How could i go about that?

[Moschops]

Open input file.
Get each word one at a time.
If word == A:
    Get the next word
    v = that next word

[vijayan121]

The file is not huge (molecules); consider reading the entire file into a data structure in memory. Perform the look ups in memory, and if the data is modified, write it back into the file at the end.

For instance: http://coliru.stacked-crooked.com/a/30d9483adc21fb9a

[SumTingWong59]

I'm getting errors in my program and i'm not too sure why, can't get much further until i get them sorted, can anyone see whats wrong?

http://pastebin.com/nVVUSkBG

[Moschops]

inData.get(A);

You're trying to feed the ifstream class function get a string. It doesn't take a string.

http://www.cplusplus.com/reference/istream/istream/get/

You can see there what paramters the get function you're trying to use can take.

[SumTingWong59]

hey Moschops, if you have time do you think we could private chat and you could help walk me through this? I understand what I need to do I'm just having a lot of trouble understanding how to go about it

Edit: and i switched it to inData >> A >> B >> b;, that should work right?