What is the difference between conversion, casting and coercion?

Question

I have been reviewing this for a long time without finding an answer, so I decide to ask: What is the difference between conversion, casting and coercion? I'm a bit clumsy with this, I really appreciate the use of a code example.

Answer 1

[C++] What is the difference between conversion, casting and coercion?

• Conversion is the creation of a value from an expression, potentially changing the type of the resulting value.

• A cast is an explicit way to convert a value. Some conversions do not require a cast. Those are called implicit conversions. Example of an implicit conversion:

  int a = 42;
  long b = a; // type of expression a is int,
              // but implicitly converted to long
  

  Same example using a cast to make the conversion explicit:

  long b = static_cast<long>(a);
  

• Type "coercion" is colloquially used as a synonym of conversion, but the term is not used in the specification of the C++ language. The term is used for example in the ECMAScript language (i.e. JavaScript). Example of a coercion in JS:

  Number("42") + 42  // == 84
  "42" + 42          // == "4242"