C Examples Duplicate Number

Here the c program for find the duplicate number

Code: Find the duplicate number and delete the number in Array

• Can be used in data processing where unique values are needed.
• Useful in student marks, sensor data, inventory numbers, or IDs.
• Demonstrates array manipulation, nested loops, and in-place removal.

#include <stdio.h>

int main() {
    int size, i, j, k;
    printf("Enter the size of the array: ");
    scanf("%d", &size);

    int Arr[size];
    printf("Enter array elements one by one:\n");
    for(i = 0; i < size; i++)
        scanf("%d", &Arr[i]);

    printf("\nOriginal Array: ");
    for(i = 0; i < size; i++)
        printf("%d\t", Arr[i]);

    // Removing duplicates
    for(i = 0; i < size; i++) {
        for(j = i + 1; j < size; j++) {
            if(Arr[i] == Arr[j]) {
                // Shift elements left
                for(k = j; k < size - 1; k++) {
                    Arr[k] = Arr[k + 1];
                }
                size--;   // Reduce array size
                j--;      // Check the new element at position j
            }
        }
    }

    printf("\nArray after removing duplicates: ");
    for(i = 0; i < size; i++)
        printf("%d\t", Arr[i]);

    return 0;
}

• Accept an array of N integers from the user.
• Identify and remove duplicate numbers from the array.
• Print the array before and after removing duplicates.

Sample Input & Output

Enter the size of the array: 6
Enter array elements one by one:
55
44
55
66
55
77

Original Array: 55    44    55    66    55    77
Array after removing duplicates: 55    44    66    77

Code Explanation for duplicate number

1. Input Array
   • User enters the size size and then size integers into Arr[].
2. Print Original Array
   • Simple loop prints all array elements.
3. Duplicate Removal Logicfor(i = 0; i < size; i++) { for(j = i + 1; j < size; j++) { if(Arr[i] == Arr[j]) { for(k = j; k < size - 1; k++) Arr[k] = Arr[k + 1]; // Shift left size--; // Reduce array size j--; // Check current index again } } }
   • Outer loop picks each element Arr[i].
   • Inner loop compares it with all following elements.
   • If a duplicate is found, shift elements left and reduce size.
   • j-- ensures we check the new element at position j.
4. Print Resulting Array
   • Loop prints the array after duplicates are removed.

Real Time use Duplicate number

Database Management

• Unique IDs: In databases, duplicate IDs (like student ID, employee ID, or product codes) must be avoided.
• Data Cleaning: Detect and remove duplicate entries to ensure accuracy in reports and analytics.

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Financial Systems

• Transactions: Prevent duplicate transaction numbers in banking or payment systems to avoid double billing.
• Invoice Management: Ensure invoices are unique to prevent errors in accounting.

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E-Commerce and Inventory

• Product Codes: Remove duplicate SKUs or barcodes to maintain correct inventory records.
• Order Tracking: Avoid duplicate order numbers to prevent shipment confusion.

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IoT & Embedded Systems

• Sensor Data: When collecting data from multiple sensors (temperature, vibration, etc.), duplicates can skew results. Removing duplicates ensures accurate real-time monitoring.
• Event Logging: In systems like security alarms, the system removes duplicate event IDs to prevent repeated alerts.

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Software & Web Applications

• User Registration: Prevent multiple accounts with the same email or username.
• Form Submissions: Avoid duplicate entries when users accidentally submit the same form multiple times.

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Data Analysis & Reporting

• Statistical Accuracy: Duplicate numbers in datasets can distort averages, totals, or trends.
• Machine Learning: Unique data points are crucial to train models correctly.

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Previous & Next

• Previous : C Examples Bitwise Operators (System Concepts)
• Next : C Examples Fibonacci Sequence

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