How to call the size of two numbers with a function--- Xiao Tang

#include <stdio.h>
{
    

void printfwelcome()
{
    
	
	
	printf("=====================================\n");
	printf("\n");
	printf("\t Welcome to Xiaotang applet !\n");
	printf("\n");
	printf("=====================================\n");
	
	
	
}

// Start encapsulating function 
int getMaxFromData(int x,int y,int z)
{
    
	int sum;
	/* if(x>y) { z=x; }else { z=y; } return z; } int getMinFromData(int x,int y) { int z; if(x<y) { z=x; }else { z=y; } return z; } */
// Three eye algorithm 
	sum=x>y?x:y;
	sum=x>z?x:z;

}

int getMinFromData(int x, int y, int z)
{
    
	int sum;
	sum=x<y?x:y;
	sum=x<z?x:z;


	
}

int main()
{
    
	
	int data1;
	int data2;
	int data3;
	int bigOne;
	int SmallOne;
	
	printfwelcome();
	printf(" Please enter three numbers ：\n");
	scanf("%d%d%d",&data1,&data2,&data3);
	bigOne=getMaxFromData(data1,data2,data3);
	SmallOne=getMinFromData(data1,data2,data3);
	printf(" The three numbers you entered are ：%d,%d,%d\n",data1,data2,data3);
	printf(" The largest of these two numbers is %d, The smallest is %d\n",bigOne,SmallOne);
	
	printf("\t Program end ！");

	return 0;
	}