Print Negative Elements in Array in C: Program to Display Negative Numbers

Introduction

In this tutorial, we will learn how to write a C program to input elements in an array and print all negative elements.

This program is useful when you need to filter and display only the negative numbers from a given set of values. It is commonly used in:

• Data analysis where negative values need to be identified
• Financial applications to detect losses or negative transactions
• Temperature data analysis to find below-zero readings
• Sensor data processing to identify negative readings

C Program to Print Negative Elements in Array

#include <stdio.h>

int main() {
    int n, i;
    int found = 0;  // Flag to check if any negative element is found
    
    // Ask user for number of elements
    printf("Enter the number of elements: ");
    scanf("%d", &n);
    
    // Declare array of size n
    int arr[n];
    
    // Read elements into the array
    printf("Enter %d elements:\n", n);
    for(i = 0; i < n; i++) {
        scanf("%d", &arr[i]);
    }
    
    // Print all negative elements
    printf("\nNegative elements in the array:\n");
    for(i = 0; i < n; i++) {
        if(arr[i] < 0) {
            printf("%d ", arr[i]);
            found = 1;
        }
    }
    
    // If no negative elements found
    if(found == 0) {
        printf("No negative elements found.\n");
    }
    printf("\n");
    
    return 0;
}

Sample Output

Enter the number of elements: 6
Enter 6 elements:
10 -5 30 -20 40 -15

Negative elements in the array:
-5 -20 -15

Another Example:

Enter the number of elements: 5
Enter 5 elements:
10 20 30 40 50

Negative elements in the array:
No negative elements found.

Example with Mixed Numbers:

Enter the number of elements: 8
Enter 8 elements:
-8 15 -23 7 -1 0 -45 99

Negative elements in the array:
-8 -23 -1 -45

Program Explanation

Let's break down the code step by step:

1. Include Header File: #include <stdio.h> includes the standard input/output library.
2. Declare Variables:
   • int n; — stores the number of elements
   • int i; — loop counter
   • int found = 0; — a flag to check if any negative element is found (0 = not found, 1 = found)
3. Get User Input: Prompts the user to enter the number of elements and then reads them into the array.
4. Print Negative Elements: The for loop iterates through each element and checks if arr[i] < 0:
   • If true, it prints the element
   • Sets found = 1 to indicate at least one negative number was found
5. Handle No Negative Elements: If found == 0, it prints a message indicating no negative elements were found.
6. Return: return 0; indicates successful program execution.

Algorithm to Print Negative Elements

1. Start
2. Read the number of elements (n)
3. Read n elements into the array
4. Set found = 0
5. For i = 0 to n-1:
   • If arr[i] < 0:
     • Print arr[i]
     • Set found = 1
6. If found == 0, print "No negative elements found"
7. End

Variation: Count Negative Elements

You can also count how many negative elements are present in the array:

#include <stdio.h>

int main() {
    int n, i;
    int count = 0;
    
    printf("Enter the number of elements: ");
    scanf("%d", &n);
    
    int arr[n];
    
    printf("Enter %d elements:\n", n);
    for(i = 0; i < n; i++) {
        scanf("%d", &arr[i]);
    }
    
    printf("\nNegative elements in the array:\n");
    for(i = 0; i < n; i++) {
        if(arr[i] < 0) {
            printf("%d ", arr[i]);
            count++;
        }
    }
    
    if(count > 0) {
        printf("\nTotal negative elements: %d\n", count);
    } else {
        printf("\nNo negative elements found.\n");
    }
    
    return 0;
}

#include <stdio.h>

int main() {
    int n, i;
    int sum = 0;
    int count = 0;
    
    printf("Enter the number of elements: ");
    scanf("%d", &n);
    
    int arr[n];
    
    printf("Enter %d elements:\n", n);
    for(i = 0; i < n; i++) {
        scanf("%d", &arr[i]);
    }
    
    printf("\nNegative elements in the array:\n");
    for(i = 0; i < n; i++) {
        if(arr[i] < 0) {
            printf("%d ", arr[i]);
            sum = sum + arr[i];
            count++;
        }
    }
    
    if(count > 0) {
        printf("\nTotal negative elements: %d\n", count);
        printf("Sum of negative elements: %d\n", sum);
    } else {
        printf("\nNo negative elements found.\n");
    }
    
    return 0;
}

/* Sample Output:
Enter the number of elements: 6
Enter 6 elements:
-5 10 -15 20 -25 30

Negative elements in the array:
-5 -15 -25
Total negative elements: 3
Sum of negative elements: -45
*/

Frequently Asked Questions

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