Convertir un nombre Décimal en Fraction

#include <stdio.h>

int main(void) {
    double a = 12.34;
    int c = 10000;
    double b = (a - floor(a)) * c;
    int d = (int)floor(a) * c + (int)(b + .5f); 
    printf("%f %d\n", b, d);

    while(1) {
       if(d % 10 == 0) {
           d = d / 10;
           c = c / 10;
       }
       else break;
    }
    printf("%d/%d\n", d, c);
    return 0;
}

Le problème est que b a été prise en 3400.00 mais quand vous ne (int) b vous obtenez 3399, vous devez ajouter des 0.5 de sorte que le nombre peut tronquer à 3400.

Arriver 3400.00 est différent que d'avoir 3400, 3400.00 signifie que le nombre a été tour à 3400, c'est pourquoi, lorsque vous n' (int) 3400.00 il suppose que l'entier le plus proche (à moins de le nombre de la conversion) est 3399, cependant, lorsque vous ajoutez 0,5 à ce numéro de la dernière l'entier le plus proche est maintenant 3400.

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Un algorithme créé avec c++ qui n'nombre décimal en fraction.

#include <iostream>
using namespace std;
//converts the string half of the inputed decimal number into numerical values
void converting (string decimalNumber, float& numerator, float& denominator )
{
float number;
string valueAfterPoint = decimalNumber.substr(decimalNumber.find(".") + 1,((decimalNumber.length() -1) )); //store the value after the decimal into a valueAfterPoint
cout << valueAfterPoint<< " "<< endl;
int length = valueAfterPoint.length(); //stores the length of the value after the decimal point into length
numerator = atof(valueAfterPoint.c_str()); //converts the string type decimal number into a float value and stores it into the numerator
//loop increases the decimal value of the numerator and the value of denominator by multiples of ten as long as the length is above zero of the decimal
cout << length<< endl;
for (; length > 0; length--)
{
numerator *= 10;
}
do
denominator *=10;
while  (denominator < numerator);
}
//simplifies the the converted values of the numerator and denominator into simpler values for          an easier to read output
void simplifying (float& numerator, float& denominator)
{
int maximumNumber = 9; //Numbers in the tenths place can only range from zero to nine so the maximum number for a position in a poisitino for the decimal number will be nine
bool isDivisble; //is used as a checker to verify whether the value of the numerator has the       found the dividing number that will a value of zero
//Will check to see if the numerator divided denominator is will equal to zero
if(int(numerator) % int(denominator) == 0)
{
numerator /= denominator;
denominator = 1;
return;
}
//check to see if the maximum number is greater than the denominator to simplify to lowest form
while (maximumNumber < denominator)
{
maximumNumber *=10;
}
//the maximum number loops from nine to zero. This conditions stops if the function isDivisible is true
for(; maximumNumber > 0; maximumNumber --)
{
isDivisble = ((int(numerator) % maximumNumber == 0) && int(denominator)% maximumNumber == 0);
cout << numerator << denominator <<" " <<endl;
if(isDivisble)
{
numerator /= maximumNumber;  //when is divisible true numerator be devided by the max    number value for example 25/5 = numerator = 5
denominator /= maximumNumber; ////when is divisible true denominator be devided by the max number value for example 100/5 = denominator = 20
}
//stop value if numerator and denominator is lower than 17 than it is at the lowest value
int stop = numerator + denominator;
if (stop < 17)
{
return;
}
}
}
int main()
{
string decimalNumber;
float numerator = 0;
float denominator = 1;
cout << "Enter the decimal number";
cin >> decimalNumber;
//convert function
converting(decimalNumber, numerator, denominator);
//call simplyfication funcition
simplifying(numerator, denominator);
cout<< "Fraction: "<< numerator << "/" << denominator<< endl;
return 0; 
}