Java program which sums numbers from 1 to 100

Question

I have been recently started learning Java and would want to make code that sums the numbers from 1 to 100 (result would be 5050)

The code should go like 1+2+3+4+5+6+7+8+

Answer 1

You have started to learn Java by implementing a for loop. Unfortunately that is probably the least intuitive syntax in the entire language. It was inherited from c and, while convenient, really makes no sense: the meaning of the three positions bears no resemblance to natural language (unlike if, while, implements etc.). Much better to start with simpler constructs until you get the hang of things.

Java 8 provides a more intuitive (in my opinion) way of representing a group of numbers to add. In your case you don't really want to iterate through all the numbers from 1 to 100. You just want a way to represent all those numbers and then sum them. In Java 8 this concept is represented by a stream of integers: the IntStream class. It provides a handy way of asking for 'all integers between x and y': the rangeClosed method. And it provides a method for adding all the integers together: the sum method.

So your operation could be implemented with a single, simple Java statement:

IntStream.rangeClosed(1, 100).sum();

That seems a pretty straightforward statement to read: give me a stream of integers in the range from 1 to 100 and then sum them. Even better you don't need to declare a variable you have no real use for.

Answer 2

Use this code. It will print the value like

1+2+3.. + 100 = 5050

public class T35{

public static void main(String[] args) {
    int total=0;

    StringBuilder stringBuilder=new StringBuilder();

    for(int nmb= 1; nmb<= 100; nmb++){

        total+=nmb;
        stringBuilder.append(nmb);
        if(nmb!=100)
        stringBuilder.append("+");

    }
    stringBuilder.append(" = "+total);
    System.out.println(stringBuilder.toString());
}

}

Answer 3

nmb++ is equal to nmb = nmb + 1. It only adds one till it's 101, which is when it stops.

You should add a new variable, let's call it total, and sum nmb to it every iteration.

public class T35{

    public static void main(String[] args) {
        int nmb;
        int total = 0;

        for(nmb= 1; nmb<= 100; nmb++){
            total = total + nmb;
        }
        System.out.println(total);

    }

}

This will do what you want.

Answer 4

Hey you can find the sum from 1 to 100 like this also. Just a option.

You can use the mathematical formula for sum of numbers i.e n(n+1)/2

public class test {

    public static void main(String[] args) {
        int i =100;
        int sum = (i)*(i+1)/2;
        System.out.println(sum);

    }
}

Answer 5

You output the value of nmb that is the numeric value that you iterate on, you don't increment the actual value with the current sum.

You should introduce a local variable before the loop to compute and maintain the actual sum.
Besides, int nmb; could be declared directly in the loop.
Narrowing the scope of variables makes the code more robust.

public class T35{

    public static void main(String[] args) {
        int sum = 0;

        for(int i= 1; i<= 100; i++){    
            sum += i;
            System.out.println(sum);    
        }    
    }

}