In this program, user first enters the count of integers that he wants to add. Then we take N integers as input from user using scanf function inside a for loop and keep on adding it to a variable sum. Once user finished entering N integers we print sum of all N integers on screen. Here we are using addition arithmetic operator('+') to add numbers.
Check this tutorial for detailed explanation of Arithmetic operators.
C program to calculate sum of N numbers using for loop and without using array
#include <stdio.h>
int main(){
int numberCount=0, number, counter, sum=0;
printf("Enter the number of integers to add: ");
scanf("%d",&numberCount);
printf("Enter %d numbers\n",numberCount);
for(counter = 0; counter < numberCount; counter++){
scanf("%d", &number);
sum = sum + number;
}
printf("SUM = %d", sum);
return 0;
}
Output
Enter the number of integers to add: 5 Enter 5 numbers 1 2 3 4 5 SUM = 15
C program to calculate sum of N numbers using array
In this program we first store all the numbers entered by user in an integer array. Then we traverse this array from index 0 to N-1 and add all numbers using a for loop and '+' operator. In line number 21, we can also uses shorthand assignment operators '+=' for addition. Check this tutorial for detailed explanation of Shorthand assignment operators.
#include <stdio.h>
int main(){
/* Using array of size 500 to store input numbers */
int numberCount=0, numbers[500], counter, sum=0;
printf("Enter the number of integers to add: ");
scanf("%d",&numberCount);
printf("Enter %d numbers\n", numberCount);
for(counter = 0; counter < numberCount; counter++){
scanf("%d", &numbers[counter]);
}
for(counter = 0; counter < numberCount; counter++){
sum = sum + numbers[counter];
}
printf("SUM = %d", sum);
return 0;
}
Output
Enter the number of integers to add: 7 Enter 5 numbers 7 6 5 4 3 2 1 SUM = 28
C program to calculate sum of N numbers using recursion
We can use recursion to find sum of N numbers by breaking a problem into smaller problem. Function "getSum(int numberCount)" takes numberCount numbers as input and adds them recursively and returns the result to calling function.
#include <stdio.h>
int getSum(int numberCount);
int main(){
int numberCount=0, number, counter, sum=0;
printf("Enter the number of integers to add: ");
scanf("%d",&numberCount);
printf("Enter %d numbers seperated by space \n", numberCount);
sum = getSum(numberCount);
printf("SUM = %d", sum);
return 0;
}
int getSum(int numberCount){
int sum=0;
/* exit condition */
if(0 == numberCount)
return 0;
scanf("%d", &sum);
/* Recursively call getSum for numberCount-1 */
return sum + getSum(numberCount - 1);
}
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