C 的入门者请进，否则不要花时间click

//只需要把下面代码paste到new project, run, 即看到效果

//The goal of this program is to show:

// the relationship of Pointer and Address in C languange.

//created by Feb 4th, 2002

//modified by Feb 4th,2004

#include <stdio.h>

#include <string.h>

#include <stdlib.h>

//if put 3, result=3^3+3=12;

//if 4, result=4^4+4=20...

double squarePlus(int a,double *b);

int main(void)

{

double x=3,y=3,result=0;

printf("\n 0.....y Address = %p\n",&y); // print y address

//scanf(y);

result=squarePlus(3,&y);

printf("\n SquarePlus of %f = %2.0f \n",x,result);

return 0;

}

/*

0.....y Address = 0012FF70

1.....pAddress(b) = 0012FF70

2.....double value(*b) = 3.000000

...processing: (*b) *= *b;

SquarePlus of 3.000000 = 12

Press any key to continue

*/

//**********************************************************//

double squarePlus(int a,double *b)

{

//Print the address of pointer:

printf(" 1.....pAddress(b) = %p \n",b);

//Print the value after calcuation:

printf(" 2.....double value(*b) = %f\n",*b);

//Save before you have to change.

double k = *b;

//b=&k; //[YES] if b= sth's address;

// *b= sth's value;

// b is always the Result:

*b=a;

(*b) *= *b; //multipile itself

printf("...processing: (*b) *= *b;\n");

*b=*b+k; //[YES] value itself +1;

//b=b+b; //[NO] just make "b" to another address;

return *b;

//return (*b)*(*b)+(*b); //[YES] works also

//return b; // [NO] cannot convert from 'double *' to 'double'

}

//http://www.eurasia.edu/bbs/ti_view.asp?FN_id=15&FC_root_id=115073&FC_id=115073