C trunc() Function

The trunc() function in C is a standard library function that truncates a given floating-point number to its integer part, effectively removing any fractional part. It is part of the C standard library (math.h). This function is useful for performing mathematical operations where only the integer part of a number is needed.

Table of Contents

  1. Introduction
  2. trunc() Function Syntax
  3. Understanding trunc() Function
  4. Examples
    • Truncating a Value
    • Using trunc() with User Input
  5. Real-World Use Case
  6. Conclusion

Introduction

The trunc() function calculates the integer part of a given floating-point number ( x ) by removing any fractional part. This function is widely used in mathematical computations and applications where only the integer part of a number is required.

trunc() Function Syntax

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

#include <math.h>
double trunc(double x);

Parameters:

  • x: The floating-point value to be truncated.

Returns:

  • The function returns the integer part of x as a floating-point number.

Understanding trunc() Function

The trunc() function takes a floating-point number ( x ) and returns the integer part of ( x ) by discarding any fractional part. The result is the integer value closest to zero.

Examples

Truncating a Value

To demonstrate how to use trunc() to truncate a value, we will write a simple program.

Example

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

int main() {
    double value = 3.14;

    // Compute the truncated value
    double result = trunc(value);

    // Print the result
    printf("Truncated value of %.2f is: %.0f\n", value, result);

    return 0;
}

Output:

Truncated value of 3.14 is: 3

Using trunc() with User Input

This example shows how to use trunc() to truncate a value provided by the user.

Example

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

int main() {
    double value;

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

    // Compute the truncated value
    double result = trunc(value);

    // Print the result
    printf("Truncated value of %.2f is: %.0f\n", value, result);

    return 0;
}

Output (example user input "7.89"):

Enter a value: 7.89
Truncated value of 7.89 is: 7

Real-World Use Case

Calculating Whole Units in Inventory Management

In real-world applications, the trunc() function can be used to calculate the number of whole units in inventory management, where fractional units are not counted.

Example: Calculating Whole Units

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

int main() {
    double total_items;
    int whole_units;

    // Get user input for the total number of items
    printf("Enter the total number of items: ");
    scanf("%lf", &total_items);

    // Calculate the number of whole units
    whole_units = (int)trunc(total_items);

    // Print the result
    printf("Number of whole units: %d\n", whole_units);

    return 0;
}

Output (example user input total items "125.75"):

Enter the total number of items: 125.75
Number of whole units: 125

Conclusion

The trunc() function is essential for truncating a floating-point number to its integer part in C. It is useful in various mathematical calculations, particularly in fields like mathematics, finance, and engineering, where only the integer part of a number is required.

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