Algorithm to count natural numbers-CodePudding

I am creating an algorithm to count natural numbers however the output is a long number:

1532752%

Here is what I have tried:

#include <stdio.h>
#include <stdlib.h>

int sumN(int N){
    int S = 0;
    int I = 1;
    int *p = &I;
    for(int i = *p; i < N; i  ){
        S  = S   i;
        I  = i   1;

        if( i <= N){
            continue;
        }
    }
    return S;
}

int main(void){
    int N = 15;
    printf("%i", sumN(N));
    return EXIT_SUCCESS;
}

I am new to C and would appreciate feedback because I am likely missing much technical information.

CodePudding user response：

Simple version

 int sum =0;
 For (int i =1; i<=N; i  ){
     sum  = i;
  }

This ignores the even simpler n*(n 1)/2 formula

CodePudding user response：

#include <stdio.h>
#include <stdlib.h>

int sumN(int N)
{
    return N*(N 1)/2;
}

int sumN2(int N)
{
    int sum = 0;
    for(int i=1; i<=N; sum =i  );
    return sum;
}

int main(void){
    int N = 15;
    printf("%i\n", sumN(N));
    printf("%i\n", sumN2(N));
    return EXIT_SUCCESS;
}

Output

120 
120

because 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 = 120