Why is this an endless loop?

Question

First of all sorry for this, I really think it is a silly question but I've been stuck on this for a while. So maybe you can help me. The problem is I don't truly understand what's wrong in the code. So let's look up.

void enter()
{
    int init= 1, end= 2;
    float jump= 0.2;
    create(init, end, jump);
}

void create(int Init, int End, float Jump)
{
    float i;
    int total = 0;
    for(i = Init; i < End; i + Jump)
        total += 1;
}

It does not exit the loop and I don't understand why.

Never, ever, ever, use floats as loop controls. Bad programmer! No biscuit! Also, your `i + jump` should be `i += jump`. — Lee Daniel Crocker, Dec 16 '14 at 18:36
There's nothing per se wrong with using floating point variables as loop controls, for instance: `for (i=1.0; i=i/2.0; i>epsilon) { ... }`. What's wrong is using floats for things that integers are better used for, particularly comparison for equality with potentially large integers. — abligh, Dec 16 '14 at 19:36

score 4 · Accepted Answer · answered Dec 16 '14 at 18:32

4

The problem is here:

i + Jump

That does not change i, it simply evaluates. Change it to this:

i += Jump

and it should work fine.

answered Dec 16 '14 at 18:32

Alexis King

43,109
15
131
205

@blackout just so it is more clear i += Jump is equivalent to i = i + Jump which modifies i. – diaz994 Dec 16 '14 at 18:40

score 2 · Answer 2 · answered Dec 16 '14 at 18:33

2

The loop is infinit because variable i is not being changed within the loop. Change this statement

for(i = Init; i < End; i + Jump)

to

for(i = Init; i < End; i += Jump)

Also maybe there is a sense to define the function as having return type int is not there? For example

int create(int Init, int End, float Jump)
{
    //...
    return total;
}

answered Dec 16 '14 at 18:33

Vlad from Moscow

301,070
26
186
335

Thank you. As I said silly question. – blackout Dec 16 '14 at 18:36

score 0 · Answer 3 · answered Dec 16 '14 at 18:33

0

i + Jump this does not modify i and hence i < End is always evaluated as TRUE, as per the initial condition (Init being less than End).

You need to change to i += End to keep incrementing the value of i.

answered Dec 16 '14 at 18:33

Sourav Ghosh

133,132
16
183
261

Why is this an endless loop?

3 Answers3