C Exercises: Get the fraction part from two given integers representing the numerator and denominator in string format

Last update on March 20 2025 12:36:15 (UTC/GMT +8 hours)

7. Fractional Part Extraction Variants

Write a C program to get the fraction part from two given integers representing the numerator and denominator in string format.

Example:
Input:
n = 3
d = 2

n = 4
d = 7
Output:
Fractional part: 1.5
Fractional part: 0.(571428)

Sample Solution:

C Code:

//Source: https://bit.ly/2KNsta8
// Header files inclusion
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>

// Function to convert a fraction to a decimal string
char* fractionToDecimal(int numerator, int denominator) {
    char *p;        // Pointer for the resulting string
    int psz, n, *dec, dsz, x; // Variables for string sizes and calculations
    long long num, den, k, f; // Variables for numerator, denominator, and calculations
    int i, repeat_at; // Loop control and repeat position variables
    int neg = 0; // Flag for negative result

    psz = dsz = 100; // Initial size for string buffers
    n = x = 0; // Initialize counters
    p = malloc(psz * sizeof(char)); // Allocate memory for the resulting string
    //assert(p); // Uncommented assert - check for allocation success

    // Determine if the result will be negative
    neg = ((numerator > 0 && denominator < 0) ||
           (numerator < 0 && denominator > 0)) ? 1 : 0;
    num = numerator;
    den = denominator;
    num = (num < 0) ? -num : num; // Make numerator positive
    den = (den < 0) ? -den : den; // Make denominator positive

    // Calculate the integer part of the result
    k = num / den;
    f = num % den;

    // If the result is negative and either the integer part or fractional part exists, append a negative sign
    if (neg && (k || f)) p[n++] = '-';

    // Append the integer part to the result string
    n += sprintf(&p[n], "%lld", k);
    if (!f) {
        p[n] = 0;
        return p;
    }

    // If fractional part exists, append a decimal point
    p[n++] = '.';

    // Allocate memory for an array to store fractional digits and their positions
    dec = malloc(dsz * sizeof(int));
    //assert(dec); // Uncommented assert - check for allocation success

    repeat_at = -1; // Initialize repeat position
    if (f < 0) f = -f; // Make the fractional part positive

    // Loop to convert fraction to decimal
    while (f) {
        // Check for repeating digits in the fractional part
        for (i = 0; i < x; i += 2) {
            if (dec[i] == f) {
                repeat_at = i;
                goto done;
            }
        }

        // If no repeating digits found, continue converting
        if (x + 1 >= dsz) {
            dsz *= 2;
            dec = realloc(dec, dsz * sizeof(int)); // Reallocate memory for the array
            //assert(dec); // Uncommented assert - check for allocation success
        }

        // Store current fractional digit and its position
        dec[x++] = f;
        f *= 10;
        k = f / den;
        dec[x++] = k;
        f = f % den;
    }

done:
    // Loop to construct the decimal string
    for (i = 0; i < x; i += 2) {
        // Check if the string buffer needs resizing
        if (n + 3 > psz) {
            psz *= 2;
            p = realloc(p, psz * sizeof(char)); // Reallocate memory for the string buffer
            //assert(p); // Uncommented assert - check for allocation success
        }

        // Add digits to the string and place '(' for repeating digits
        if (repeat_at == i) {
            p[n++] = '(';
        }
        p[n++] = '0' + dec[i + 1];
    }

    // Add ')' if repeating digits were found
    if (repeat_at != -1) p[n++] = ')';
    p[n++] = 0; // Null-terminate the string

    free(dec); // Free memory allocated for the fractional digits array

    return p; // Return the resulting string
}

// Main function to test the fractionToDecimal function with different values
int main(void) {
    int n = 3;
    int d = 2;
    printf("\nn = %d, d = %d  ", n, d);
    printf("\nFractional part: %s ", fractionToDecimal(n, d)); // Display result for n/d
    n = 4;
    d = 7;
    printf("\n\nn = %d, d = %d  ", n, d);
    printf("\nFractional part: %s ", fractionToDecimal(n, d)); // Display result for n/d
    return 0;
}

Sample Output:

n = 3, d = 2  
Fractional part: 1.5 

n = 4, d = 7  
Fractional part: 0.(571428) 

Flowchart:

For more Practice: Solve these Related Problems:

• Write a C program to compute the fractional part of a division and represent recurring decimals with parentheses.
• Write a C program to extract the fractional part from two integers and format the result as a mixed fraction.
• Write a C program to calculate and display the fractional part by performing long division manually.
• Write a C program to convert the fraction obtained from two integers into a string showing non-repeating and repeating parts.

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