Vigenere Decipher/Encipher

This is a discussion on Vigenere Decipher/Encipher within the C++ Programming forums, part of the General Programming Boards category; I am new here and a very novice. I want to learn something from you. Here my codes won't work ...

  1. #1
    Registered User
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    Feb 2002
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    Angry Vigenere Decipher/Encipher

    I am new here and a very novice. I want to learn something from you. Here my codes won't work . any idea or suggestion? any help would be appreciated.

    void vigenere(operation){
    var keyText = trimString(document.forms[0].keyfield.value);
    if (keyText == ""){
    return;
    }
    for (i = 0; i < keyText.length; i++){
    letter = keyText.charAt(i).toLowerCase();
    if ("abcdefghijklmnopqrstuvwxyz".indexOf(letter) == -1){
    alert("Your key may contain only letters.");
    return;
    }
    }
    if (operation == "encipher"){
    var inputText = document.forms[0].plainfield.value;
    outputText = vencipher(inputText,keyText);
    document.forms[0].cipherfield.value = outputText;
    }
    else if (operation == "decipher"){
    var inputText = document.forms[0].cipherfield.value;
    outputText = vdecipher(inputText,keyText);
    document.forms[0].plainfield.value = outputText;
    }
    else{
    alert("Error");
    }
    }

    void vencipher(inputText,keyText){
    var letterOffset;
    var inputNumber;
    var outputNumber;
    var changeNumber;
    var iKey = 0;
    var outputChar = "";
    var outputText = "";
    var lowerAlpha = "abcdefghijklmnopqrstuvwxyz";
    var upperAlpha = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    keyText = keyText.toLowerCase();
    for (i = 0; i < inputText.length; i++){
    inputChar = inputText.charAt(i);
    if (upperAlpha.indexOf(inputChar) != -1){
    var alphabet = upperAlpha;
    }
    else if (lowerAlpha.indexOf(inputChar) != -1){
    var alphabet = lowerAlpha;
    }
    else {
    outputText += inputChar;
    continue;
    }
    inputNumber = alphabet.indexOf(inputChar);
    changeNumber = lowerAlpha.indexOf(keyText.charAt(iKey));
    outputNumber = inputNumber + changeNumber;
    outputNumber -= (outputNumber >= 26) ? 26 : 0;
    outputChar = alphabet.charAt(outputNumber);
    outputText += outputChar;
    iKey++;
    iKey = (iKey >= keyText.length) ? 0 : iKey;
    }
    return outputText;
    }

    void vdecipher(inputText,keyText){
    var letterOffset;
    var inputNumber;
    var outputNumber;
    var changeNumber;
    var iKey = 0;
    var outputChar = "";
    var outputText = "";
    var lowerAlpha = "abcdefghijklmnopqrstuvwxyz";
    var upperAlpha = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    keyText = keyText.toLowerCase();
    for (i = 0; i < inputText.length; i++){
    inputChar = inputText.charAt(i);
    if (upperAlpha.indexOf(inputChar) != -1){
    var alphabet = upperAlpha;
    }
    else if (lowerAlpha.indexOf(inputChar) != -1){
    var alphabet = lowerAlpha;
    }
    else {
    outputText += inputChar;
    continue;
    }
    inputNumber = alphabet.indexOf(inputChar);
    changeNumber = lowerAlpha.indexOf(keyText.charAt(iKey));
    outputNumber = inputNumber - changeNumber;
    outputNumber += (outputNumber < 0) ? 26 : 0;
    outputChar = alphabet.charAt(outputNumber);
    outputText += outputChar;
    iKey++;
    iKey = (iKey >= keyText.length) ? 0 : iKey;
    }
    return outputText;
    }

    void clearForm(){
    document.forms[0].plainfield.value = "";
    document.forms[0].cipherfield.value = "";
    }

    void trimString(inputString) {
    var outputString = "";
    var front = 0;
    while ((front < inputString.length) && (inputString.charAt(front) == ' ')){
    ++front;
    }
    var back = inputString.length;
    while ((back > 0) && (inputString.charAt(back - 1) == ' ')){
    --back;
    }
    outputString = inputString.substring(front, back);
    return outputString;
    }

  2. #2
    Mayor of Awesometown Govtcheez's Avatar
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    Let me guess... You used to program in Java, right? Pretty much the whole program is messed up. You don't have a main function, you declare variables wrong, you use Java (charAt is Java, not C), and you appear to make up your own language in places. My advice: Put this program away for awhile (Maybe a month or so), grab a book, and relearn C++ from the ground up (hmm... that'd make a good book title).

  3. #3
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    how can i change to C? not Java. thanks in advance.

  4. #4
    Mayor of Awesometown Govtcheez's Avatar
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    You're going to have to rewrite all of the code. Well, to be fair, not all of it. About 90% of it. Look on the web for tutorials on C, and you'll see what I'm talking about.

  5. #5
    Fingerstyle Guitarist taylorguitarman's Avatar
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    564
    Looks like JavaScript to me, not Java. There is a large difference for those that don't know. Anyways, as Govtcheez said, you're going to have to rewrite it. Get a good book on C++ or Java and write it according to the way that language does it. I think in this case Java would be an easier translation but you're going to have to learn a new language either way. You get to choose
    If a tree falls in the forest, and no one is around to see it, do the other trees make fun of it?

  6. #6
    5|-|1+|-|34|) ober's Avatar
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    I think that's a combination of Java and Javascript... see above for advice...

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