When do you use the “this” keyword? [closed]

Answer 1

I use it when, in a function that accepts a reference to an object of the same type, I want to make it perfectly clear which object I'm referring to, where.

For example

class AABB
{
  // ... members
  bool intersects( AABB other )
  {
    return other.left() < this->right() &&
           this->left() < other.right() &&

           // +y increases going down
           other.top() < this->bottom() &&
           this->top() < other.bottom() ;
  }
} ;

(vs)

class AABB
{
  bool intersects( AABB other )
  {
    return other.left() < right() &&
           left() < other.right() &&

           // +y increases going down
           other.top() < bottom() &&
           top() < other.bottom() ;
  }
} ;

At a glance which AABB does right() refer to? The this adds a bit of a clarifier.

Answer 2

I pretty much only use this when referencing a type property from inside the same type. As another user mentioned, I also underscore local fields so they are noticeable without needing this.

Answer 3

It depends on the coding standard I'm working under. If we are using _ to denote an instance variable then "this" becomes redundant. If we are not using _ then I tend to use this to denote instance variable.

Answer 4

I use it to invoke Intellisense just like JohnMcG, but I'll go back and erase "this->" when I'm done. I follow the Microsoft convention of prefixing member variables with "m_", so leaving it as documentation would just be redundant.

Answer 5

Here's when I use it:

• Accessing Private Methods from within the class (to differentiate)
• Passing the current object to another method (or as a sender object, in case of an event)
• When creating extension methods :D

I don't use this for Private fields because I prefix private field variable names with an underscore (_).

Answer 6

I only use it when absolutely necessary, ie, when another variable is shadowing another. Such as here:

class Vector3
{
    float x;
    float y;
    float z;

    public Vector3(float x, float y, float z)
    {
        this.x = x;
        this.y = y;
        this.z = z;
    }

}

Or as Ryan Fox points out, when you need to pass this as a parameter. (Local variables have precedence over member variables)