डबल से फ्लोट या "पेनी कहाँ गया?"

99999999.33333333 -> 100000000.0000000 98888888.33333333 -> 98888888.0000000 2974815.78000000 -> 2974815.7500000 

 public class Main { static void testDoubleToFloat(double d) { float f = (float) d; System.out.println(); System.out.println(String.format("double %.10f\t%s", d, Long.toBinaryString(Double.doubleToRawLongBits(d)))); System.out.println(String.format("float %.10f\t %s", f, Integer.toBinaryString(Float.floatToRawIntBits(f)))); } public static void main(String[] args) { System.out.println(String.format("double: %.10f / %.10f", Double.MIN_VALUE, Double.MAX_VALUE)); System.out.println(String.format("float: %.10f / %.10f", Float.MIN_VALUE, Float.MAX_VALUE)); /*  ,        double. */ testDoubleToFloat(99999999.0 + 1.0 / 3.0); //   testDoubleToFloat(98888888.0 + 1.0 / 3.0); //     testDoubleToFloat(2974815.78); testDoubleToFloat(-2974815.78); } } 

 double: 0.0000000000 / 179769313486231570000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000.0000000000 float: 0.0000000000 / 340282346638528860000000000000000000000.0000000000 double 99999999.3333333300 100000110010111110101111000001111111101010101010101010101010101 float 100000000.0000000000 1001100101111101011110000100000 double 98888888.3333333300 100000110010111100100111011001011100001010101010101010101010101 float 98888888.0000000000 1001100101111001001110110010111 double 2974815.7800000000 100000101000110101100100010111111100011110101110000101000111101 float 2974815.7500000000 1001010001101011001000101111111 double -2974815.7800000000 1100000101000110101100100010111111100011110101110000101000111101 float -2974815.7500000000 11001010001101011001000101111111 

 /opt/jdk1.7/bin/java -version java version "1.7.0_25" Java(TM) SE Runtime Environment (build 1.7.0_25-b15) Java HotSpot(TM) 64-Bit Server VM (build 23.25-b01, mixed mode) 

 java -version java version "1.7.0_25" OpenJDK Runtime Environment (IcedTea 2.3.12) (7u25-2.3.12-4ubuntu3) OpenJDK 64-Bit Server VM (build 23.7-b01, mixed mode) 

रूपांतरण विधि

 public class Main { static void testDoubleToFloat(double d) { float f = (float) d; Float f2 = new Float(d); float f3 = Float.parseFloat(new Double(d).toString()); float f4 = Float.parseFloat(String.format("%.10f", d)); System.out.println(); System.out.println(String.format("double %.10f\t%s", d, Long.toBinaryString(Double.doubleToRawLongBits(d)))); System.out.println(String.format("float %.10f\t %s", f, Integer.toBinaryString(Float.floatToRawIntBits(f)))); System.out.println(String.format("Float %.10f\t %s", f2, Integer.toBinaryString(Float.floatToRawIntBits(f2)))); System.out.println(String.format("float %.10f\t %s", f3, Integer.toBinaryString(Float.floatToRawIntBits(f3)))); System.out.println(String.format("float %.10f\t %s", f4, Integer.toBinaryString(Float.floatToRawIntBits(f4)))); } public static void main(String[] args) { System.out.println(String.format("double: %.10f / %.10f", Double.MIN_VALUE, Double.MAX_VALUE)); System.out.println(String.format("float: %.10f / %.10f", Float.MIN_VALUE, Float.MAX_VALUE)); testDoubleToFloat(99999999.0 + 1.0 / 3.0); testDoubleToFloat(98888888.0 + 1.0 / 3.0); testDoubleToFloat(2974815.78); testDoubleToFloat(-2974815.78); } } 

  double: 0.0000000000 / 179769313486231570000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000.0000000000 float: 0.0000000000 / 340282346638528860000000000000000000000.0000000000 double 99999999.3333333300 100000110010111110101111000001111111101010101010101010101010101 float 100000000.0000000000 1001100101111101011110000100000 Float 100000000.0000000000 1001100101111101011110000100000 float 100000000.0000000000 1001100101111101011110000100000 float 100000000.0000000000 1001100101111101011110000100000 double 98888888.3333333300 100000110010111100100111011001011100001010101010101010101010101 float 98888888.0000000000 1001100101111001001110110010111 Float 98888888.0000000000 1001100101111001001110110010111 float 98888888.0000000000 1001100101111001001110110010111 float 98888888.0000000000 1001100101111001001110110010111 double 2974815.7800000000 100000101000110101100100010111111100011110101110000101000111101 float 2974815.7500000000 1001010001101011001000101111111 Float 2974815.7500000000 1001010001101011001000101111111 float 2974815.7500000000 1001010001101011001000101111111 float 2974815.7500000000 1001010001101011001000101111111 double -2974815.7800000000 1100000101000110101100100010111111100011110101110000101000111101 float -2974815.7500000000 11001010001101011001000101111111 Float -2974815.7500000000 11001010001101011001000101111111 float -2974815.7500000000 11001010001101011001000101111111 float -2974815.7500000000 11001010001101011001000101111111 

 /* * Copyright (c) 1994, 2010, Oracle and/or its affiliates. All rights reserved. * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms. */ ... public final class Float extends Number implements Comparable<Float> { ... public Float(double value) { this.value = (float)value; } ... } 

  return (float)Double.longBitsToDouble( lbits ); 

 float f = (float) d; 

फ्लोट और डबल स्टोरेज प्रारूप

  double 2974815.7800000000 100000101000110101100100010111111100011110101110000101000111101 float 2974815.7500000000 1001010001101011001000101111111 

  double 2974815.7800000000 0 10000010100 0110101100100010111111100011110101110000101000111101 float 2974815.7500000000 0 10010100 01101011001000101111111 

• 1 बिट 0 => सकारात्मक संकेत
• आगे के प्रदर्शक: 010000010100 ₂ -1023 ₁₀ = 21
  
  और 10010100 ₂ -127 ₁₀ = 21
  
• मंटिसा: १.०११०११००१०००१११११११११ पर ०१११०१११ पर, ११०००००००१००० पर, ११०११११ _२ * २ ^{२१ - ५२} = २ ^९ 15४15१५.9999 ९९९९ ⁴⁹ ९
  
  और 1.01101011001000101111111 ₂ * 2 ^{21 - 23} = 2974815.75
  

निष्कर्ष

पुनश्च

• फ़्लोट को ठीक करें। सही ढंग से राउंड करने के लिए फ़्लोट करें और एकरसता को संरक्षित करें। - हमने पहले ही पता लगा लिया कि ऐसा क्यों हो रहा है
• प्रत्यक्ष स्ट्रिंग-टू-फ्लोट रूपांतरण एकरूपता को संरक्षित नहीं करता है - एक ही बात

ग्राहक द्वारा काम किया गया:
मध्यवर्ती डबल्स का उपयोग करके सीधे स्ट्रिंग-टू-फ्लोट रूपांतरण से बचना।

प्रस्तावित समाधान

1. BigDecimal बैंकों में पैसे जमा करें:
   

     BigDecimal bg = new BigDecimal("2974815.78"); System.out.println(bg); 

   
   
2. मुद्रा वर्ग प्रकार से:
   

    class Currency { long value; ... public double asDouble() { return value / 100.0; } ... <   ,  ..   , ,  StringTokenizer> ... } 

   
   मुझे लगता है कि निर्णय में अन्य त्रुटियां / विशेषताएं शामिल होंगी, हालांकि इसमें जीवन का अधिकार है।