C program using do-while loop to check inside or outside

Understanding the Problem

• Goal: Write a C program that takes coordinates (x, y) from the user and determines whether the point lies inside or outside a circle of radius 5 centered at (0, 0).
• Key Concepts:
  • Loops: do-while loop for repeated input and checking.
  • Conditional statements: if-else for decision-making.
  • Mathematical calculations: Distance formula for checking distance from the center.
  • Input/Output (I/O): scanf for input, printf for output.

Step-by-Step Guide

1. Header Inclusion

C

#include <stdio.h>
#include <math.h>  // For sqrt() function

• Explanation: Include the standard input/output library and math library.

2. Main Function

C

int main() {
    // Code statements here
    return 0;
}

3. do-while Loop for Repeated Input

C

do {
    // Get coordinates from the user
    int x, y;
    printf("Enter coordinates (x, y): ");
    scanf("%d %d", &x, &y);

    // Calculate distance from the center
    double distance = sqrt(pow(x, 2) + pow(y, 2));  // Distance formula

    // Check if inside or outside
    if (distance <= 5) {
        printf("Point (%d, %d) is inside the circle.\n", x, y);
    } else {
        printf("Point (%d, %d) is outside the circle.\n", x, y);
    }

    // Ask if the user wants to continue
    char choice;
    printf("Do you want to check another point? (y/n): ");
    scanf(" %c", &choice);  // Note the space before %c to consume newline
} while (choice == 'y' || choice == 'Y');

4. Explanation of Code:

• do-while loop: Ensures at least one iteration of input and checking.
• scanf(“%d %d”, &x, &y): Reads the coordinates entered by the user.
• distance = sqrt(pow(x, 2) + pow(y, 2)): Calculates the distance from the point to the center using the distance formula.
• if-else statement: Determines whether the distance is less than or equal to 5 (inside) or greater than 5 (outside).
• printf statements: Print the result to the console.
• scanf(” %c”, &choice): Reads the user’s choice to continue or not (note the space before %c to consume the newline character).

5. Complete Code

C

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

int main() {
    do {
        int x, y;
        printf("Enter coordinates (x, y): ");
        scanf("%d %d", &x, &y);

        double distance = sqrt(pow(x, 2) + pow(y, 2));

        if (distance <= 5) {
            printf("Point (%d, %d) is inside the circle.\n", x, y);
        } else {
            printf("Point (%d, %d) is outside the circle.\n", x, y);
        }

        char choice;
        printf("Do you want to check another point? (y/n): ");
        scanf(" %c", &choice);
    } while (choice == 'y' || choice == 'Y');

    return 0;
}

6. Executing the Program

1. Save the code as a .c file (e.g., inside_outside.c).
2. Compile using a C compiler (e.g., gcc inside_outside.c -o inside_outside).
3. Run the executable (e.g., ./inside_outside).

I hope this guide is helpful!