Functions

• Little programs
• You should use them. (Who wants to write big programs?)
  • Easier to create
  • Easier to test
  • Easier to debug
  • Easier to modify
  • Easier to understand
• Everything must be declared before it is used.
• Type 1, C style

  #include <iostream>
  
  using namespace std;
  
  void hello() { 
      cout << hello << endl;
  }
  
  int main () {
     hello();
  }
      

  • The procedure is declared before the procedure is used.
• Type 2, C++ style

  #include <iostream>
  
  using namespace std;
  
  void hello();
  
  int main () {
     hello();
  }
  
  void hello() { 
      cout << hello << endl;
  }
      

  • A function prototype is declared before the procedure is used.
  • The procedure is declared later in the code.
• Calling vs called
• Parameters
• Formal declaration and parameter list
• arguments, argument list
• Flow of control
• Return value
• Value vs variable parameters
• Local variables