C1815: <Name> not declared (or typename)

[ERROR]

Description

The specified identifier was not declared.

Example
  void main(void) {

  
    i=2;

  
  }

  
Tips

A variable's type must be specified in a declaration before it can be used. The parameters that a function uses must be specified in a declaration before the function can be used. This error can be caused, if an include file containing the required declaration was omitted.