Thread: Passing Structures ??

Heres how I do it.

Code:

struct temp {
  char strg1[ N ],strg2[ N ];
  int test[ N ];
  float fraction;
};

somefunction( struct temp theStruct[ ] );

main( void ) {
  struct temp S1[ 100 ];
  FILE *fp;

  somefunction( S1 );

  return 0;
}

You put the structure definition outside the main so that other functions can define a structure ( like defining a char or int ). The file pointer is just fine inside main.

Okay, so the structure is global... okay I get that, how do i send the file pointer to functions other than main() ?? also, in the function, how do i redeclare the structure?


somefunction(s2) {

}

would that work ?? or do i need more?

Since the type FILE is defined in c lib:

Code:

struct temp {
  char strg1[ N ],strg2[ N ];
  int test[ N ];
  float fraction;
};

  /* prototype: you have declared a structure 
  ** that will "carry" what you pass */
somefunction( struct temp theStruct[ ], FILE *theFilePointer );

main( void ) {
  struct temp S1[ 100 ];
  FILE *fp;

  somefunction( S1, fp );

  return 0;
}

somefunction( struct temp theStruct[ ], FILE *theFilePointer ) {
  /* because the struct definition is global you 
  ** can declare another structure as well */
  struct temp anotherStruct;
  /* but this is a completely seperate new struct, just the same type */
}

Just as you declared the FILE *fp; in main you can also declare variables in functions. Like:

Code:

someFunction( ) {
  char myChar;
  int myInt;
  /* doing other function stuff */
}

However variables declared in a function, even in main are not accessible by other functions. The way to create access points is by passing parameters or returning values.

Returning a value:

Code:

int someFunction( ) {
  char myChar;
  int myInt;
  /* doing other function stuff */

  return 1; 
}

When this function finishes it will return the value 1 to whatever called it. You can return pretty much anything, but only one thing at a time. To utilize a return is as simple as this:

int myInt;

myInt = someFunction( );