Rules of Writing Function : C Programming

Rules of Writing Function in C Programming

Rule 1. C program is a collection of one or more functions

main()
{
pune();
mumbai();
maharashtra();
}

Rule 2. A function gets called when the function name is followed by a semicolon.

For example :

main( )
 {
 display( ) ;
 }

Rule 3 : A function is defined when function name is followed by a pair of braces in which one or more statements may be present.

For example,

display( )
      {
      statement 1 ;
      statement 2 ;
      statement 3 ;
      }

Rule 4. Any function can be called from any other function.( main also )

main( )
{
 message( ) ;
}
 message( )
   {
   printf ( "\nWe are going to call main" ) ;
   main( ) ;
   }

Rule 5.A function can be called any number of times.

For example,

main()
{
message( );
message( );
}
message()
{
printf("\nLearning C is very Easy");
}

Rule 6. The order in which the functions are defined in a program and the order in which they get called need not necessarily be same

main( )
      {
      message1( ) ;
      message2( ) ;
      }
      message2( )
      {
      printf ( "\n I am First Defined But Called Later " ) ;
      }
      message1( )
      {
      printf ( "\n I am Defined Later But Called First ") ;
      }

Rule 7. A function can call itself ( Process of Recursion )

int fact(int n)
{
 if(n==0)
  return(1);
 return(n*fact(n-1));
}

Rule 8. A function can be called from other function, but a function cannot be defined in another function.