C modf() Function

The modf() function in C is a standard library function that breaks a floating-point number into its fractional and integral parts. It is part of the C standard library (math.h). This function is useful for separating the fractional and integral components of a floating-point number.

Table of Contents

1. Introduction
2. modf() Function Syntax
3. Understanding modf() Function
4. Examples
   • Breaking a Number into Fractional and Integral Parts
   • Using modf() with User Input
5. Real-World Use Case
6. Conclusion

Introduction

The modf() function decomposes a floating-point number into its fractional and integral parts. The integral part is stored in a separate variable, while the function returns the fractional part.

modf() Function Syntax

The syntax for the modf() function is as follows:

#include <math.h>
double modf(double x, double *intpart);

Parameters:

• x: The floating-point number to be decomposed.
• intpart: A pointer to a variable where the integral part of the number will be stored.

Returns:

• The function returns the fractional part of the number x.

Understanding modf() Function

The modf() function separates a floating-point number into its fractional and integral parts. The fractional part is returned by the function, while the integral part is stored in the variable pointed to by intpart.

Examples

Breaking a Number into Fractional and Integral Parts

To demonstrate how to use modf() to break a number into its fractional and integral parts, we will write a simple program.

Example

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

int main() {
    double value = 3.14;
    double intpart;

    // Break the value into fractional and integral parts
    double fracpart = modf(value, &intpart);

    // Print the result
    printf("Value: %.2f\n", value);
    printf("Integral part: %.2f\n", intpart);
    printf("Fractional part: %.2f\n", fracpart);

    return 0;
}

Output:

Value: 3.14
Integral part: 3.00
Fractional part: 0.14

Using modf() with User Input

This example shows how to use modf() to break a user-provided number into its fractional and integral parts.

Example

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

int main() {
    double value, intpart;

    // Get user input for the value
    printf("Enter a floating-point value: ");
    scanf("%lf", &value);

    // Break the value into fractional and integral parts
    double fracpart = modf(value, &intpart);

    // Print the result
    printf("Value: %.2f\n", value);
    printf("Integral part: %.2f\n", intpart);
    printf("Fractional part: %.2f\n", fracpart);

    return 0;
}

Output (example user input "5.67"):

Enter a floating-point value: 5.67
Value: 5.67
Integral part: 5.00
Fractional part: 0.67

Real-World Use Case

Handling Monetary Values

In real-world applications, the modf() function can be used to separate the dollar and cent parts of a monetary value.

Example: Handling Monetary Values

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

int main() {
    double amount, dollars;

    // Get user input for the monetary amount
    printf("Enter the monetary amount: ");
    scanf("%lf", &amount);

    // Break the amount into dollar and cent parts
    double cents = modf(amount, &dollars);

    // Print the result
    printf("Amount: $%.2f\n", amount);
    printf("Dollars: $%.2f\n", dollars);
    printf("Cents: %.2f\n", cents * 100);  // Convert fractional part to cents

    return 0;
}

Output (example user input "123.45"):

Enter the monetary amount: 123.45
Amount: $123.45
Dollars: $123.00
Cents: 45.00

Conclusion

The modf() function is essential for breaking a floating-point number into its fractional and integral parts in C. It is useful in various applications, particularly in fields like finance and engineering, where such decomposition of numbers is required.