Sum Odd numbers from [A B] diapason

// Program is suming odd numbers from [A B] diapason


#include <stdio.h>

#include <stdlib.h>







int main(){

int r,i,a,b, sum=0;

scanf("%d %d", &a, &b);  // We should write two number. A and B. Program will sum odd numbers From A to B



r=(b-a);       // how many numbers do we have from 12 to 20? result=20-12=8  

int mass[r];   // so we have r numbers




// if A is odd

if (a%2!=0) {  

for(i=0; i<=r; i+=2)

    {

    mass[i]=a+i;  // odd numbers by 2 step. For example if first number is 13 the next will be 13+2, the next 13+2+2


         if (i>0)

	     printf("+%d", mass[i]);  // if we write only  "%d+ " the result will be, for example, 5+7+=12 the + near is not beautiful. si this code is to remove the "="

         else

	     printf("%d", mass[i]);


    sum=sum+mass[i];

    }

printf("= %d \n", sum);


}

//////////////////////////////////////////////////////////////







// IF A is even number

else if (a%2==0){

for(i=0; i<=r; i+=2)    

    {

    mass[i]=a+i+1;  // odd numbers by 2 step. For example if first number is 12 the next will be 12+2+1

    if (mass[i]>b)  continue;   // From [a,b] diapason, Array Also tooks  b+1, If B is even, SO we could use function "continue;" 


           if (i>0)

           printf("+%d", mass[i]);

           else

           printf("%d", mass[i]);


    sum=sum+mass[i];   // we could write sum+=mass[i]; this is same;

    }

printf("=%d \n", sum);  // to write sum


}



}

For example, If we write 11 27, program will write:
11+13+15+17+19+21+23+25+27=171

Edited by VakhoQ, 20 December 2010 - 03:35 AM.