C Program to Add n Numbers

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In this article, you will learn and get code about how to add n numbers (n integer numbers, n real numbers, and n natural numbers) in C programming. Here n indicates the amount/quantity. That is, how many numbers, user wants to enter and add them as shown here.

For example, if user enters 5 as the value of n, then program further ask from user to enter any 5 number. After receiving 5 numbers say 10, 20, 30, 40, and 50 from user, program sum-up all the 5 numbers and display its summation as result on output. That will be 150 (because 10+20+30+40+50 equals 150).

Find Sum of n Numbers in C

To add n numbers in C programming, you have to ask from user to enter the value of n, then ask to enter n numbers to perform the addition of all the provided n numbers (by user). And then display the addition result as output on screen. Let's take a look at the program.

#include<stdio.h>
#include<conio.h>
int main()
{
    int i, n, num, sum=0;
    printf("Enter the value of n: ");
    scanf("%d", &n);
    printf("Enter %d numbers: ", n);
    for(i=0; i<n; i++)
    {
        scanf("%d", &num);
        sum = sum+num;
    }
    printf("\nSum of all %d numbers = %d", n, sum);
    getch();
    return 0;
}

This program was written under Code::Blocks IDE. Here is the initial snapshot of sample run:

Supply the value of n say 6, then enter any 6 integer values say 10, 20, 30, 40, 50, 60 and press ENTER key to see the output as shown in the second snapshot of sample run:

Steps used in above Program

Some of the main steps used in above program are:

Declare required amount of variable that is i, n, num and sum
Initialize sum with 0
Receive the value of n
Use for loop to receive desired amount of numbers
Inside the for loop, we have applied the summation operation each time when receiving the number
That is, when user enters first number say 10, then sum+num or 0+10 gets initialized to sum
Again when user enters second number say 20, then sum+num or 10+20 gets initialized to sum
Process the operation for all numbers. That is, if user enters 6 as value of n, then operation goes 6 times
Print the value of sum

What if User enters Decimal Numbers ?

The program given above is correct only when user supply all the numbers in integer form (without any decimal). So here is the modified version of the above program that is correct for both integer and decimal numbers.

This program is applicable to find the sum of all n real numbers.

#include<stdio.h>
#include<conio.h>
int main()
{
    int n, i;
    float num, sum=0;
    printf("Enter the value of n: ");
    scanf("%d", &n);
    printf("Enter %d numbers: ", n);
    for(i=0; i<n; i++)
    {
        scanf("%f", &num);
        sum = sum+num;
    }
    printf("\nSum of all %d numbers = %0.2f", n, sum);
    getch();
    return 0;
}

Here is the snapshot of first sample run. In this sample run, we have provided all the numbers as integer value:

And here is the snapshot of second sample run. In this sample run, we have provided all the numbers as floating-point value:

In above program, we only done these changes:

Declared num and sum variable as float data type for real number operation
For both variable, %f format specifier used here
0.2f is used to print the value of sum upto 2 decimal places
Rest of the program is same as above one

C Program to Find Sum of N Natural Numbers

As we all knows that positive numbers from 1, 2, 3, ... are natural numbers. Therefore here we only have to ask from user, the value of n, that is upto how many term, the natural number continues, and find sum of that natural number.

For example, if user enters the value of n as 8, then find sum of first 8 natural number, that will be 1, 2, 3, 4, 5, 6, 7 and 8. Let's take a look at the program:

#include<stdio.h>
#include<conio.h>
int main()
{
    int i, n, sum=0;
    printf("Enter the value of n: ");
    scanf("%d", &n);
    for(i=1; i<=n; i++)
        sum = sum+i;
    printf("\nSum of %d natural numbers = %d", n, sum);
    getch();
    return 0;
}

Here is the snapshot of sample run:

Same Program in Other Languages

C Online Test

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