langc_pointer_argtest.c

#include <stdio.h>

#define CNT_TEST	2

int map[20]={0};  // save address info 
int size=0;

int map2[20]={0};  // save address info 
int size2=0;


/* 
   for this pointer argument test

   any pointer arguments can change that value but can't change pointer address value if just used one pointer (*)   
   if you want to change pointer address in sub function, try to use double pointer (**) 
   
*/

int setDataVoid(void *data)  // cant change this point argument 
{
	map[size++]=data;	
	printf("void * set addr=%x \n",data);
	return 0;
}

int getDataVoid(void* data) // when you read void * data , there is a problem 
{
	if(size==0)	return -1;
	data = (void *) map[--size];
	printf("void * get addr=%x \n",data);
	return 0;
}

int getDataVoid2(void** data) // when you read void ** data , there is no problem 
{
	if(size==0)	return -1;
	*data = (void *) map[--size];
	printf("void ** get addr=%x \n",*data);
	
	return 0;
}




int getDataInt(int * data) // when you read int * data , there is a problem 
{
	if(size2==0)	return -1;
	data = (int *) map2[--size2];
	printf("int * get addr=%x \n", data);
	return 0;
}

int setDataInt(int *data)  // cant change this point argument 
{
	map2[size2++]=data;	
	printf("int * set addr=%x \n",data);
	return 0;
}




int main(void) {
	int data[]={10,11,12,13,14,15,16,17,18,19,20,21};
	int getdata=0;
	int *pdata;
	int i;
	
	int cnt;
	
	cnt = sizeof(data);
	cnt = cnt > CNT_TEST ?  CNT_TEST:cnt;
	
	printf("Void * Pointer \n");
	
	for(i=0;i<cnt;i++)
		setDataVoid((void *)&data[i]);
		
	printf("\n");
	
	for(i=0;i<cnt;i++)
	{
		getDataVoid((void*)&getdata); // can't get this value 
		printf("Void * after called get addr=%x \n",getdata);		
	}
	
	printf("\nVoid** Pointer \n");
	getdata=0;
	
	for(i=0;i<cnt;i++)
		setDataVoid((void *)&data[i]);
		
	printf("\n");
	
	for(i=0;i<cnt;i++)
	{	
		getDataVoid2((void*)&getdata);
		pdata=getdata;		
		printf("Void ** after called get addr=%x data=%d \n",getdata,*pdata);		
	}	
	
	printf("\nINT Pointer \n");
	getdata=0;
	
	for(i=0;i<cnt;i++)
		setDataInt(&data[i]);

	printf("\n");
		
	for(i=0;i<cnt;i++)
	{	
		getDataInt(&getdata);
	//	pdata=getdata;		
		printf("int * after called get addr=%x \n",getdata);		
	}	
	
	return 0;
}