C에서 부동 소수점을 이진 표현 프로그램으로 변환

Question

#include "ieee754.h" 
#include <stdio.h> 
#include <math.h> 

//This program convert a floating number to its binary representation 
(IEEE754) in computer memory 
int main() 
{ 

long double f, binaryTotal, binaryFrac = 0.0, frac, fracFractor = 0.1; 
long int integer, binaryInt = 0; 
long int p = 0, rem, temp; 

printf("\nEnter floating number: "); 
scanf("%Lf",&f); 

//separate the integer part from the input floating number 
integer = (int)f; 

//separate the fractional part from the input floating number 
frac = f - integer; 

//loop to convert integer part to binary 
while(integer != 0) 
{ 
    rem = integer % 2; 
    binaryInt = binaryInt + rem *pow(10,p); 
    integer = integer/2; 
    p++; 
} 

//loop to convert fractional part to binary 
while(frac != 0) 
{ 
    frac = frac * 2; 
    temp = frac; 
    binaryFrac = binaryFrac + fracFractor * temp; 
    if (temp == 1) 
     frac = frac - temp; 

    fracFractor = fracFractor/10 ; 


} 

binaryTotal = binaryInt + binaryFrac; 
printf("binary equivalent = %Lf\n", binaryTotal); 


} 

부동 소수점을 이진 표현 (64 비트)으로 변환하려고합니다. 이 코드는 작동하지만 완벽하지는 않습니다. 예를 들어 나는 0.575를 변환 할 때, 그것은 나에게 0.100100을 제공하지만이 웹 사이트 http://www.exploringbinary.com/floating-point-converter/를 사용하여 변환을 할 때 문제가 내 코드 수를 절단하는 무슨 이해하는 데 0.1001001100110011001100110011001100110011001100110011

오른쪽 출력해야한다. 아무도 그것을 고칠 수있는 방법을 도와 줄래? 도와 주셔서 감사합니다. 이 작업을하지 않을 이유

Answer 1

은 다음과 같습니다

fracFractor = 0.1 
... 
fracFractor = fracFractor/10 

0.1은 이진 부동 소수점 형식으로 정확하게 표시 할 수 없습니다. 0.1을 2의 음수 배수로 나타낼 수 없습니다. 10으로 나누면 모든 단계에서 반올림 오류가 수집됩니다. 반복되는 분수와 다른 반복 분수를 비교하기 때문에 실제로 종료 할 수 있습니다.

그리고 이것은 심각하게 당신이 달성 할 수있는 제한됩니다

binaryTotal = binaryInt + binaryFrac; 

부동 소수점에서 이렇게 심각한 제한이있을 것이다 -이 아닌 이상에서 상술 한 바와 같이 0.1을 대표하는 표현할 수없는 것을. 그렇기 때문에 이진수와 십진수가 혼합 된 답변을 얻을 수 있습니다.

이 문제를 해결하려면 숫자의 개별 비트를 살펴 봐야합니다. 솔루션의 전체적인 아이디어를 그대로 유지하려면 분수에서 2의 음수 (0.5, 0.25 등)를 빼고 계속 긍정적인지 테스트하고이를 기반으로 문자열을 작성하는 것이 가장 쉽습니다. 그런 다음 정수 부분에 대해 유사한 논리를 사용하십시오.

Answer 2

많은 문제 :

long double의 정수 부분이 심각 범위를 제한 추출 (int) 사용

1. . modfl(long double value, long double *iptr);

   long double f; 
   long int integer; 
   //separate the integer part from the input floating number 
   // Weak code 
   integer = (int)f; 
   
   long double ipart; 
   long double fpart = modfl(f, &ipart); 
   

2. long p; pow(10,p); 사용 - 한 번 ppow() 반환 값의 정밀도> 손실은 몇 가지 값 (예 : 25)를 초과합니다. 또한 long double을 사용하는 기능을 가진 pow()을 사용하는 것이 이상합니다. 나는 powl()을 기대합니다.

3. 기타 다양한 부정확 한 FP 문제 : fracFractor/10, 제한된 정밀도 long.

FP 번호 (일부 바이너리 형식 일 가능성이 있음)를 바이너리 표현으로 변환하려고하면 코드가 이상합니다. 코드 내의 어느 곳에서나 10이 필요하지 않습니다.

을 사용할 모든 경고와

#include<stdio.h> 
#include<stdlib.h> 
#include<math.h> 
#include<float.h> 

static void print_ipart(long double x) { 
    int digit = (int) (modfl(x/2, &x)*2.0) + '0'; 
    if (x) { 
    print_ipart(x); 
    } 
    putchar(digit); 
} 

void print_bin(long double x) { 
    // Some TBD code 
    // Handle NAN with isnan() 
    // Handle infinity with isfinite() 

    putchar(signbit(x) ? '-' : '+'); 

    long double ipart; 
    long double fpart = modfl(fabsl(x), &ipart); 

    print_ipart(ipart); 
    putchar('.'); 
    while (fpart) { 
    long double ipart; 
    fpart = modfl(fpart * 2, &ipart); 
    putchar((int)ipart + '0'); 
    } 
    putchar('\n'); 
} 

int main() { 
    print_bin(-4.25); 
    print_bin(.575); 
    print_bin(DBL_MAX); 
    print_bin(DBL_MIN); 
    print_bin(DBL_TRUE_MIN); 
} 

출력

-100.01 
+0.1001001100110011001100110011001100110011001100110011001100110011 
+1111111111111111111111111111111111111111111111111111100000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000. 
+0.00000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001 
+0.000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000001