can we use if else statement in a function cpp code example

Example 1: elseif c++

if( a == 10 ) {
      cout << "Value of a is 10" << endl;
   } else if( a == 20 ) {
      // if else if condition is true
      cout << "Value of a is 20" << endl;
   }

Example 2: c++ how to do else if statements

if (variable) {
  variable is true 
  }