Chgt de base !

Question

Bjr a tous, je suis nouveau ici et g une kestion a poser !
Je voudrais savoir comment passer, en java, d'une base n ( infèrieure ou égale a 36 ) en base 10 !!

G déja fé moi meme l'inverse, c a d passer un nombre en base 10 vers n'importe kelle base ( inférieure ou égale a 36 ) . Voici mon code ( il marche !!) :

class Base   //---------Passage Base 10 en Base n
{
public static void main(String[] arg)
{
int nombre=13, base=2,quotient, suite;
String symboles="0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ", resul="";
quotient=nombre;
while(quotient>0)
{
suite=quotient%base;
resul=symboles.charAt(suite)+resul;
quotient=quotient/base;
}
System.out.println(resul);
    }
}

J'aimerias savoir comment faire l'inverse. Merci a tous ceux ki pourront m'aider !

_____SergiO_____

cs_GodConan · Answer

GodConan :clown) 

bon je t fait sa rapide  avec le main pour exmple :

    public static void main(String[] args)
    {   // exemple
        String s = convertValueBaseXToBase10( "AA", 16 );
        System.out.println( "AA = " + s );
    }
    
    static String SYMBOLES="0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    public static String convertValueBaseXToBase10( String value, int baseValue )
    {
        long result = 0;
        int max = value.length()-1;
        for (int i = max; i >= 0; i--)
            result += SYMBOLES.indexOf( value.charAt( i ) ) 
                    * Math.pow( baseValue, max - i );
        return ""+result;
    }

j espere c ce kil te fallai ... ;o) c pour tan pas bien dur... ;o)

GL
++

cs_neodante · Answer

:big) Neodante :big) Pour info, voici la classe officielle de SUN attention c'est long ... y a même un main() ! /* * @(#)Base64.java 1.4 03/01/23 * * Copyright 2003 Sun Microsystems, Inc. All rights reserved. * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */ package java.util.prefs; /** * Static methods for translating Base64 encoded strings to byte arrays * and vice-versa. * * @author Josh Bloch * @version 1.4, 01/23/03 * @see Preferences * @since 1.4 */ class Base64 { /** * Translates the specified byte array into a Base64 string as per * Preferences.put(byte[]). */ static String byteArrayToBase64(byte[] a) { return byteArrayToBase64(a, false); } /** * Translates the specified byte array into an "aternate representation" * Base64 string. This non-standard variant uses an alphabet that does * not contain the uppercase alphabetic characters, which makes it * suitable for use in situations where case-folding occurs. */ static String byteArrayToAltBase64(byte[] a) { return byteArrayToBase64(a, true); } private static String byteArrayToBase64(byte[] a, boolean alternate) { int aLen = a.length; int numFullGroups = aLen/3; int numBytesInPartialGroup = aLen - 3*numFullGroups; int resultLen = 4*((aLen + 2)/3); StringBuffer result = new StringBuffer(resultLen); char[] intToAlpha = (alternate ? intToAltBase64 : intToBase64); // Translate all full groups from byte array elements to Base64 int inCursor = 0; for (int i=0; i> 2]); result.append(intToAlpha[(byte0 << 4)&0x3f | (byte1 >> 4)]); result.append(intToAlpha[(byte1 << 2)&0x3f | (byte2 >> 6)]); result.append(intToAlpha[byte2 & 0x3f]); } // Translate partial group if present if (numBytesInPartialGroup != 0) { int byte0 = a[inCursor++] & 0xff; result.append(intToAlpha[byte0 >> 2]); if (numBytesInPartialGroup == 1) { result.append(intToAlpha[(byte0 << 4) & 0x3f]); result.append("=="); } else { // assert numBytesInPartialGroup == 2; int byte1 = a[inCursor++] & 0xff; result.append(intToAlpha[(byte0 << 4)&0x3f | (byte1 >> 4)]); result.append(intToAlpha[(byte1 << 2)&0x3f]); result.append('='); } } // assert inCursor == a.length; // assert result.length() == resultLen; return result.toString(); } /** * This array is a lookup table that translates 6-bit positive integer * index values into their "Base64 Alphabet" equivalents as specified * in Table 1 of RFC 2045. */ private static final char intToBase64[] = { 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H', 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P', 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X', 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '/' }; /** * This array is a lookup table that translates 6-bit positive integer * index values into their "Alternate Base64 Alphabet" equivalents. * This is NOT the real Base64 Alphabet as per in Table 1 of RFC 2045. * This alternate alphabet does not use the capital letters. It is * designed for use in environments where "case folding" occurs. */ private static final char intToAltBase64[] = { '!', '"', '#', '$', '%', '&', '\'', '(', ')', ',', '-', '.', ':', ';', '<', '>', '@', '[', ']', '^', '`', '_', '{', '|', '}', '~', 'a', 'b', 'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', 'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', '0', '1', '2', '3', '4', '5', '6', '7', '8', '9', '+', '?' }; /** * Translates the specified Base64 string (as per Preferences.get(byte[])) * into a byte array. * * @throw IllegalArgumentException if s is not a valid Base64 * string. */ static byte[] base64ToByteArray(String s) { return base64ToByteArray(s, false); } /** * Translates the specified "aternate representation" Base64 string * into a byte array. * * @throw IllegalArgumentException or ArrayOutOfBoundsException * if s is not a valid alternate representation * Base64 string. */ static byte[] altBase64ToByteArray(String s) { return base64ToByteArray(s, true); } private static byte[] base64ToByteArray(String s, boolean alternate) { byte[] alphaToInt = (alternate ? altBase64ToInt : base64ToInt); int sLen = s.length(); int numGroups = sLen/4; if (4*numGroups != sLen) throw new IllegalArgumentException( "String length must be a multiple of four."); int missingBytesInLastGroup = 0; int numFullGroups = numGroups; if (sLen != 0) { if (s.charAt(sLen-1) == '=') { missingBytesInLastGroup++; numFullGroups--; } if (s.charAt(sLen-2) == '=') missingBytesInLastGroup++; } byte[] result = new byte[3*numGroups - missingBytesInLastGroup]; // Translate all full groups from base64 to byte array elements int inCursor 0, outCursor 0; for (int i=0; i> 4)); result[outCursor++] = (byte) ((ch1 << 4) | (ch2 >> 2)); result[outCursor++] = (byte) ((ch2 << 6) | ch3); } // Translate partial group, if present if (missingBytesInLastGroup != 0) { int ch0 = base64toInt(s.charAt(inCursor++), alphaToInt); int ch1 = base64toInt(s.charAt(inCursor++), alphaToInt); result[outCursor++] = (byte) ((ch0 << 2) | (ch1 >> 4)); if (missingBytesInLastGroup == 1) { int ch2 = base64toInt(s.charAt(inCursor++), alphaToInt); result[outCursor++] = (byte) ((ch1 << 4) | (ch2 >> 2)); } } // assert inCursor == s.length()-missingBytesInLastGroup; // assert outCursor == result.length; return result; } /** * Translates the specified character, which is assumed to be in the * "Base 64 Alphabet" into its equivalent 6-bit positive integer. * * @throw IllegalArgumentException or ArrayOutOfBoundsException if * c is not in the Base64 Alphabet. */ private static int base64toInt(char c, byte[] alphaToInt) { int result = alphaToInt[c]; if (result < 0) throw new IllegalArgumentException("Illegal character " + c); return result; } /** * This array is a lookup table that translates unicode characters * drawn from the "Base64 Alphabet" (as specified in Table 1 of RFC 2045) * into their 6-bit positive integer equivalents. Characters that * are not in the Base64 alphabet but fall within the bounds of the * array are translated to -1. */ private static final byte base64ToInt[] = { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1, -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51 }; /** * This array is the analogue of base64ToInt, but for the nonstandard * variant that avoids the use of uppercase alphabetic characters. */ private static final byte altBase64ToInt[] = { -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, -1, 62, 9, 10, 11, -1 , 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 12, 13, 14, -1, 15, 63, 16, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 17, -1, 18, 19, 21, 20, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 22, 23, 24, 25 }; public static void main(String args[]) { int numRuns = Integer.parseInt(args[0]); int numBytes = Integer.parseInt(args[1]); java.util.Random rnd = new java.util.Random(); for (int i=0; i

cs_GodConan · Answer

GodConan :clown) 

ouai ben la mienne est plus simple ;o) hihi...

 :-p  :-p  :-p  :-p  :-p  :-p

cs_neodante · Answer

:big) Neodante :big) 

Ah oui je comprends ...
 lol lol lol lol ... attends je mets des smiley  :-p  :-p  :-p  :-p  :-p  :-p  :-p  :-p  :-p  !
Oups j'avais aps vu que c'était aussi long !
 :big) 
@+

cs_Argel · Answer

Votre méthode marche très bien mé je n'ai po très bien compris son fonctionnement...je suis débutant ds Java !
J'aimerais savoir ce ke fé la fonction Math.pow() et si on peu la remplacer par autre chose...
_____SergiO_____

cs_neodante · Answer

:big) Neodante :big) 
pow power puissance !
@+

Chgt de base !

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