How do you find out addition of all numbers between two inputed numbers in for loop?

Answer 1

First of all we will describe how our program should be working.

After entering number 1 and 5 I want it count 2 + 3 + 4 and return 9. After entering 4 and 9 it should count 5 + 6 + 7 + 8 and return 26. After entering X and X I should get 0. If I enter X and X - 1 I should get and error.

Here is the code of such application:

#include

int main() {

int firstNum, secondNum, sum, tmp;

printf("Please enter first number: ");

scanf("%d", &firstNum);

printf("Please enter second number: ");

scanf("%d", &secondNum);

if (secondNum < firstNum) {

printf("Sorry, second number must be higher than first one.\n");

return 1;

}

sum = 0;

for (tmp = firstNum + 1; tmp < secondNum; tmp++) {

sum += tmp;

}

printf("All numbers between %d and %d sum equals %d\n", firstNum, secondNum, sum);

return 0;

}

Testing:

Please enter first number: 1

Please enter second number: 5

All numbers between 1 and 5 sum equals 9

Please enter first number: 4

Please enter second number: 9

All numbers between 4 and 9 sum equals 26