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

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