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[Ronald_mcd]

disclaimer - I am very new to C.
I am making a program that will split a chemical up into its elements, then find the molar mass of the chemical. Right now I am able to split it up into tokens (ie, split 2NaCl into 2, Na, and Cl.) My problem is when I have something like CH3COOH and one of my tokens is H3, I don't know how to split them up so I can multiply the H(1.01) by the 3.

my code so far.

#include <ctype.h>
#include <stdio.h>


char *GetToken(char sFormula[], int *iStartPos, int iLength)
{
    int iRetValue=0;
    int iIndex=0;
    static char sTempString[80];
    
     
    
    if(isupper(sFormula[*iStartPos]))
    {                        
       do
        {
        sTempString[iIndex]=sFormula[*iStartPos];
        (*iStartPos)++;
        iIndex++;
        }while(!(isupper(sFormula[*iStartPos])));
       sTempString[iIndex]='\0';
       }
    return sTempString;
}



int GetNumber(char sFormula[], int *iStartPos, int iLength)
{
    int iRetValue=1;
    int iIndex=0;
    char sTempString[80];
    
    if(isdigit(sFormula[*iStartPos]))
    {                        
       do
        {
       sTempString[iIndex]=sFormula[*iStartPos];
        (*iStartPos)++;
        iIndex++;
        }while(isdigit(sFormula[*iStartPos]));
       sTempString[iIndex]='\0';
       iRetValue=atoi(sTempString);
       }
   return iRetValue;
}




int main()
{
char sFormula[80];
char sToken[80];
int iOverAllMultiplier;
int iIndex, iLength;

printf("Enter the Chemical Formula\n");
gets(sFormula);



iLength=strlen(sFormula);
for (iIndex=0; iIndex<iLength;iIndex++)
    {
    if ((sFormula[iIndex]=='+') || (sFormula[iIndex]=='=') || (sFormula[iIndex]==' '))
    break;
    }
sFormula[iIndex]='\0';
iLength=iIndex;

iIndex=0   ;
 iOverAllMultiplier=GetNumber(sFormula, &iIndex, iLength);
 printf("Overall multiplier is %d\n ", iOverAllMultiplier);

while (iIndex<iLength)
{
strcpy(sToken, GetToken(sFormula, &iIndex, iLength));
printf("our token is : %s\n ", sToken);
}





      system("PAUSE");
      return 0;
}

 

[Lathentar]

Go crazy and write a finite state machine!

 

[Phoenix]

Separate the wheat from the chaff - once you have a token break it into its characters and numbers. Numbers at the end would be yoru subscript.