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POIndex Error: List Index out of range
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copied!<p>This is my first time posting in stackoverflow, so I hope I'm doing everything right in terms of site etiquette. I am in a beginning programming class (Python), and my current assignment is to calculate the molecular weight of a compound of Carbon, Hydrogen, and Oxygen, given a user input. It can be anything from C2 to C8H19O2, and so on. </p> <p>I have my code and I keep getting an error I am unfamiliar with. Essentially what I am trying to do is have the code read the input compound character by character determining if it is a molecule or not. Then, it reads the character to the right of the previous character to determine if that is a number of another compound. If it is a different compound, then the previous single compound is added to a running tally of whichever molecule it was' total. if it is a number, then it will read the next character to the right to once again determine if it is a number or character. If it is a number, it multiplies the previous character number by 10 and then adds the next one, and so on, until it reaches the next character(C123H2 would be 10*1 + 2 followed by 10*12 + 3, and then it would add 123 Carbons to the running tally). Once our runny tallies are complete, then that number is multiplied by the molecular weight of one of each. I keep getting an index error that says my list index is out of range. Any help is greatly appreciated!</p> <p>def main():</p> <pre><code>C1 = 0 H1 = 0 O1 = 0 num = 0 chemicalFormula = (input("Enter the chemical formula, or enter key to quit: ")) while True: cformula = list(chemicalFormula) for index, x in enumerate(cformula): if x == 'C': if cformula[index + 1] == 'H' or cformula[index + 1] == 'O': C1 += 1 else: for index, y in enumerate(range(index + 1, 1000000000)): if cformula[index + 1] != 'H' or cformula[index + 1] != 'O': num = int(y) num = num*10 + int(cformula[index + 1]) else: C1 += num break elif x == 'H': if cformula[index + 1] == 'C' or cformula[index + 1] == 'O': H1 += 1 else: for y in range(index + 1, 1000000000): if cformula[index + 1] != 'C' or cformula[index + 1] != 'O': num = int(y) num = num*10 + cformula[index + 1] else: H1 += num break elif x == 'O': if cformula[index + 1] == 'C' or cformula[index + 1] == 'H': O1 += 1 else: for y in range(index + 1, 1000000000): if cformula[index + 1] != 'C' or cformula[index + 1] != 'H': num = int(y) num = num*10 + cformula[index + 1] else: O1 += num break else: break weightC = 15.994*C1 weightH = 1.0079*H1 weightO = 12.011*O1 sumWeight = weightC + weightH + weightO print("The molecular weight is ", sumWeight) </code></pre>

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