find the rightmost and leftmost number in a point cloud of text file

[des6043]

Hi,everyone. I am trying to do a program about convex hull. But i am stuck in the first step. That is find the rightmost and leftmost point in the point cloud. In the text file,there have 33456 points. Can anyone help me in this problem? Because i am still a beginner in c++ programming. I will appreciate for your help. Thanks.

[ne555]

The rightmost point is the one with the biggest 'x' value.
The leftmost point is the one with the lowest 'x' value.

¿what is the problem?

[des6043]

Sorry, i didn't mention well in my question just now. I mean if i write a program. How can i ask the program to detect the rightmost and leftmost number inside the point cloud file? there are 33456points in the text file. I need to read the text file. then find the rightmost and leftmost point.

[ne555]

max_element( s.begin(), s.end(), check_out_the_x_coordinate );
It may be a good idea to store the points in a container, to avoid several traverses of the file.

[bluecoder]

or could it be that reading the file one by one line getting the right most error and then comaparing the elements like the function

int compare(int a, int b) 
{
  return ( a > b) ? a : b ; 
}

please correct me if i am wroing .. i agree with ne555 from the performance point of view are the point are in large number .

[des6043]

ok. Thanks guys. I am using this code to read my file. How can i compare it?
Because i am doing computer graphics also. So it may consists some opengl terms.
Or anyone know any website that i can refer to? As my tutorial. Cause i am still new in programming.

#include "graphics.h"

#include <iostream>
void CPrimitive::LoadObject(char *file, CPrimitive *obj = new CPrimitive)
{
	FILE*fp = fopen(file,"r");

	fscanf(fp,"%d",&TempNum);
	obj->NumTri = TempNum;
	for(i=0;i<obj->NumTri;i++)
	{
		fscanf(fp,"%f %f %f", &A[i].x,&A[i].y,&A[i].z);
		fscanf(fp,"%f %f %f", &B[i].x,&B[i].y,&B[i].z);
		fscanf(fp,"%f %f %f", &C[i].x,&C[i].y,&C[i].z);
	}

	fclose(fp);
}

void CPrimitive::Draw(CPrimitive *obj=new CPrimitive)
{
	glPushMatrix();
	glBegin(GL_POINTS);
	for(int j=0;j<obj->NumTri;j++)
	{
		glVertex3fv(&A[j].x);
		glVertex3fv(&B[j].x);
		glVertex3fv(&C[j].x);
	}


	glEnd();
	glPopMatrix();
}