57 lines
1.5 KiB
Java
57 lines
1.5 KiB
Java
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public class BinaryConverter
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{
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public static void main(String[] args)
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{
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for(int i = -5; i < 33; i++)
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{
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System.out.println(i + ": " + toBinary(i));
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System.out.println(i);
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//always another way
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System.out.println(i + ": " + Integer.toBinaryString(i));
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}
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}
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/*
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* pre: none
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* post: returns a String with base10Num in base 2
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*/
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public static String toBinary(int base10Num)
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{
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boolean isNeg = base10Num < 0;
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base10Num = Math.abs(base10Num);
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String result = "";
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while(base10Num > 1)
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{
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result = (base10Num % 2) + result;
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base10Num /= 2;
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}
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assert base10Num == 0 || base10Num == 1 : "value is not <= 1: " + base10Num;
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result = base10Num + result;
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assert all0sAnd1s(result);
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if( isNeg )
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result = "-" + result;
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return result;
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}
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/*
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* pre: cal != null
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* post: return true if val consists only of characters 1 and 0, false otherwise
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*/
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public static boolean all0sAnd1s(String val)
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{
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assert val != null : "Failed precondition all0sAnd1s. parameter cannot be null";
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boolean all = true;
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int i = 0;
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char c;
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while(all && i < val.length())
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{
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c = val.charAt(i);
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all = c == '0' || c == '1';
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i++;
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}
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return all;
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}
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}
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