How create an input box having a + and - button in Ionic

As for ionic v.1 at your template you could have something like:

<div class="flex_row">
  <button class="button icon ion-minus-circled red" ng-click="sub(item)">
  <p> {{item.quantity}} </p>
  <button class="button icon ion-plus-circled green" ng-click="add(item)">
</div>

At your css

    .red:before {
    color: red;
    }

    .green:before {
    color: green;
    }

    .flex_row {
    display: -webkit-flex;
    display: flex;
    -webkit-flex-direction: row; 
    flex-direction: row;
    }

And in your controller

$scope.sub = function(i) {
  i.quantity--;
}

$scope.add = function(i) {
  i.quantity++;
}

Here's a quickly thrown together example for Ionic 2. If you are using Ionic 1 you should be able to adapt it pretty easily.

You just need a couple controller/class functions to increment and decrement, then call those on tap from the buttons. This example covers just one button, so something like this wrapped in an ngFor or a <ion-list>

page.ts:

private currentNumber = 0;
constructor () { }

private increment () {
  this.currentNumber++;
}

private decrement () {
  this.currentNumber--;
}

page.html:

<ion-icon name="remove-circle" (click)="decrement()">
{{currentNumber}}
<ion-icon name="add-circle" (click)="increment()">