Clearing the terminal screen - c++

Question

#include <iostream>
#include <math.h>
#include <cstdlib>
using namespace std;
void circle(int x, int y, int radius);
void line(int a, int b, int c, int d);
bool buffer[26][81];
char drawSpace[26][81];
int main() {
int a = 0;
int b = 0;
int c = 0;
int d = 0;
int x = 0;
int y = 0;
int radius = 0;
char choice;
cout << "Type 'c' to draw a circle or type 'l' to draw a line." << endl;
cin >> choice;
if (choice == 'c'){
cout << "please enter an x coordinate for the center of the circle \n";
cin >> x;
cout << "please enter a y coordinate for the center of the circle \n";
cin >> y;
cout << "please enter a value for the radius of the circle \n";
cin >> radius;
int moves = (x - radius) / 10;
for (int s = 0; s < moves; s++){
circle(x, y, radius);
system("clear");
x = x -10;
}
}
else if (choice == 'l'){
cout << "Please enter the x coordinate for the first point on the line \n";
cin >> a;
cout << "Please enter the y coordinate for the first point on the line \n";
cin >> b;
cout << "Please enter the x coordinate for the end point on the line \n";
cin >> c;
cout << "Please enter the y coordinate for the end point on the line \n";
cin >> d;
}
else
cout << "you did not enter an appropriate letter, please restart the program and try again."<< endl;
return 0;
}
void circle(int x, int y, int radius){
if (x + radius >= 81|| x - radius <= 0 || y + radius >= 26 || y - radius <= 0){
cout << "the coordinates provided for the circle will not fit on the screen" << endl;
return;
}
for (int i = 0; i < 26; i++) {
for(int j = 0; j < 81; j++) {
int a = abs (x - j);
int b = abs (y - i);
int distance = pow(a, 2) + pow(b, 2);
int realDistance = pow(radius, 2);
if (abs(realDistance - distance) <= 3){
buffer[i][j] = true;
}
}
}
for (int m = 0; m < 26; m++){
for(int n = 0; n < 81; n++){
if (buffer[m][n]){
drawSpace[m][n] = 42;
}
else
drawSpace[m][n] = 32;
}
}
for (int row = 25; row >= 0; row--) {
for (int col = 0; col < 81; col++) {
cout << drawSpace[row][col];
}
cout << "\n";
}
}
void line(int a, int b, int c, int d){
if (a >= 81 || c >= 81 || a <= 0 || c <= 0 || b >= 26 || d >= 26 || b <= 0 || d <= 0){
return;
}
int intercept = 0;
double rise = d - b;
double run = c - a;
double slope = rise/run;
intercept = b - (slope*a);
for (int i = 0; i < 26; i++) {
for(int j = 21; j < 81; j++) {
if (slope > 0){
if (j > a && j < c){
int newIntercept = i - (slope*j);
int test = abs (intercept - newIntercept);
if (test <= 0)
buffer[i][j] = true;
else
buffer[i][j] = false;
}
}
else if (slope < 0){
if (j < a && j > c){
int newIntercept = i - (slope*j);
int test = abs (newIntercept - intercept);
if (test <= 0)
buffer[i][j] = true;
}
else
break;
}
}
}
for (int m = 0; m < 26; m++){
for(int n = 0; n < 81; n++){
if (buffer[m][n])
drawSpace[m][n] = 42;
else
drawSpace[m][n] = 32;
}
}
for (int row = 25; row >= 0; row--) {
for (int col = 0; col < 81; col++) {
cout << drawSpace[row][col];
}
cout << "\n";
}
}
I have written this code for a programming assignment, the goal of which is to take inputs for the coordinates and dimensions of a circle or line, and to print them out to the terminal as if it were a graph. The second step is to get the shape to move from the right side of the screen to the left. I have started to write this code for the circle, however for some reason the system("clear") call does not seem to clear the screen, and it simply prints extra circles without getting rid of the older one. If someone could help I would really appreciate it.

Answer 1

Try:
cout << "\033[2J\033[1;1H";
Go http://en.wikipedia.org/wiki/ANSI_escape_code for more information.

Answer 2

On Linux (and other Unixes) you could also use the ncurses library to output to a terminal.

Answer 3

The original poster doesn't have enough rep yet, so I'm posting this here for him:
I was actually a bit off base. The system("clear") I was using actually did
work, the problem I was encountering was that I did not reset the bool
array I was using to plot out the points that needed to be drawn.
Thanks for the help, I learned a few things about how to clear the screen before I found my own problem.