I try to write a simple console application in C++ which can read any chemical formula and afterwards compute its molar mass, for example:
- Na2CO3, or something like:
- La0.6Sr0.4CoO3, or with brackets:
- Fe(NO3)3
The problem is that I don't know in detail how I can deal with the input stream. I think that reading the input and storing it into a char vector may be in this case a better idea than utilizing a common string.
My very first idea was to check all elements (stored in a char vector), step by step: When there's no lowercase after a capital letter, then I have found e.g. an element like Carbon 'C' instead of "Co" (Cobalt) or "Cu" (Copper). Basically, I've tried with the methods isupper(...), islower(...) or isalpha(...).
// first idea, but it seems to be definitely the wrong way
// read input characters from char vector
// check if element contains only one or two letters
// ... and convert them to a string, store them into a new vector
// ... finally, compute the molar mass elsewhere
// but how to deal with the numbers... ?
for (unsigned int i = 0; i < char_vec.size()-1; i++)
{
if (islower(char_vec[i]))
{
char arr[] = { char_vec[i - 1], char_vec[i] };
string temp_arr(arr, sizeof(arr));
element.push_back(temp_arr);
}
else if (isupper(char_vec[i]) && !islower(char_vec[i+1]))
{
char arrSec[] = { char_vec[i] };
string temp_arrSec(arrSec, sizeof(arrSec));
element.push_back(temp_arrSec);
}
else if (!isalpha(char_vec[i]) || char_vec[i] == '.')
{
char arrNum[] = { char_vec[i] };
string temp_arrNum(arrNum, sizeof(arrNum));
stoechiometr_num.push_back(temp_arrNum);
}
}
I need a simple algorithm which can handle with letters and numbers. There also may be the possibility working with pointer, but currently I am not so familiar with this technique. Anyway I am open to that understanding in case someone would like to explain to me how I could use them here.
I would highly appreciate any support and of course some code snippets concerning this problem, since I am thinking for many days about it without progress… Please keep in mind that I am rather a beginner than an intermediate.
