C++ Remove the last new line - c++

Question

I'm using cout and endlto print some guides, the output (my intention) is like:
From Spot 1
Spot 2
Spot 5
Spot 8
Spot 6
To Spot 3
Here, the Spot No. is random and generated from some iterations. Because of iterations, i can only print the result like:
From Spot 1
Spot 2
Spot 5
Spot 8
Spot 6
Spot 3
Is there any method to remove my last new line Spot 3?
EDIT:
I want to find the shortest path (using Floyd-Warshall Algorithm) between two vertices. Here's my code, and it describes the following gragh:
#include <iostream>
using namespace std;
const int INF = 100000;
int n = 10, path[11][11], dist[11][11], map[11][11];
void init() {
int i, j;
for ( i = 1; i <= n; i++ )
for ( j = 1; j <= n; j++ )
map[i][j] = ( i == j ) ? 0:INF;
map[1][2] = 2, map[1][4] = 20, map[2][5] = 1;
map[3][2] = 3, map[4][3] = 8, map[4][6] = 6;
map[4][7] = 4, map[5][3] = 7, map[5][8] = 3;
map[6][3] = 1, map[7][8] = 1, map[8][6] = 2;
map[8][10] = 2, map[9][7] = 2, map[10][9] = 1;
}
void floyd() {
int i, j, k;
for ( i = 1; i <= n; i++ )
for ( j = 1; j <= n; j++ )
dist[i][j] = map[i][j], path[i][j] = 0;
for ( k = 1; k <= n; k++ )
for ( i = 1; i <= n; i++ )
for ( j = 1; j <= n; j++ )
if ( dist[i][k] + dist[k][j] < dist[i][j] )
dist[i][j] = dist[i][k] + dist[k][j], path[i][j] = k;
}
void output( int i, int j ) {
if ( i == j ) return;
if ( path[i][j] == 0 ) cout << "Spot" << j << endl;
else {
output( i, path[i][j] ); // iterations
output( path[i][j], j );
}
}
int main() {
int u, v;
init();
floyd();
u = 1, v = 3;
if ( dist[u][v] == INF ) cout << "No path" << endl;
else {
cout << "From Spot" << u << endl;
output( u, v );
cout << endl;
}
return 0;
}
The problem now is to find the conditon of the last iteration so that i can cout a different expression. But i think it is more easier to solve the problem by simply removing the last expression and rewriting, so i didnt attach my code.
EDIT 2:
I've achieved my purpose with the help of Fabian Tamp though it seems a little stupid of me writing the code above. Here goes the modified code:
#include <iostream>
#include <queue>
using namespace std;
const int INF = 100000;
int n = 10, path[11][11], dist[11][11], map[11][11];
void init() {
int i, j;
for ( i = 1; i <= n; i++ )
for ( j = 1; j <= n; j++ )
map[i][j] = ( i == j ) ? 0:INF;
map[1][2] = 2, map[1][4] = 20, map[2][5] = 1;
map[3][3] = 3, map[4][3] = 8, map[4][6] = 6;
map[4][7] = 4, map[5][3] = 7, map[5][8] = 3;
map[6][3] = 1, map[7][8] = 1, map[8][6] = 2;
map[8][10] = 2, map[9][7] = 2, map[10][9] = 1;
}
void floyd() {
int i, j, k;
for ( i = 1; i <= n; i++ )
for ( j = 1; j <= n; j++ )
dist[i][j] = map[i][j], path[i][j] = 0;
for ( k = 1; k <= n; k++ )
for ( i = 1; i <= n; i++ )
for ( j = 1; j <= n; j++ )
if ( dist[i][k] + dist[k][j] < dist[i][j] )
dist[i][j] = dist[i][k] + dist[k][j], path[i][j] = k;
}
void output( int i, int j, queue<int> &output_queue ) {
if ( i == j ) return;
if ( path[i][j] == 0 ) output_queue.push(j);
else {
output( i, path[i][j], output_queue); // iterations
output( path[i][j], j, output_queue);
}
}
void print_path(queue<int> output_queue) {
if (output_queue.empty()) return;
int item = output_queue.front();
while (!output_queue.empty()) {
item = output_queue.front();
output_queue.pop();
if (output_queue.empty()) {
cout << "To ";
}
cout << "Spot " << item << endl;
}
}
int main() {
int u, v;
init();
floyd();
u = 1, v = 3;
if ( dist[u][v] == INF ) cout << "No path" << endl;
else {
cout << "From Spot " << u << endl;
queue<int> output_queue;
output(u, v, output_queue);
print_path(output_queue);
}
return 0;
}
The output is the guide at the very beginning. Thank you all!

Answer 1

Change your output function thusly:
void output( int i, int j, Queue<int> &output_queue ) {
if ( i == j ) return;
if ( path[i][j] == 0 ) output_queue.push(j);
else {
output( i, path[i][j], output_queue); // iterations
output( path[i][j], j, output_queue);
}
}
Then change your main():
//....
else {
Queue<int> output_queue;
output_queue.push(u);
output(u, v, output_queue);
print_path(output_queue);
}
//...
Then add print_path:
void print_path(Queue<int> output_queue) {
if (output_queue.empty()) return;
auto item = output_queue.front();
cout << "From Spot " << item << endl;
while (!output_queue.empty()) {
item = output_queue.front();
output_queue.pop();
if (output_queue.empty()) {
cout << "To ";"
}
cout << "Spot " << item << endl;
}
}
A couple of things here:
I haven't compiled or tested this. Try and figure out any errors yourself and letting me know in the comments.
It would be really helpful for you to look at the STL. http://www.cplusplus.com/reference is a great resource for this.
If you're not familiar with passing by reference, that's the strategy I used to make sure that we're adding information to the same output_queue. Note that I've passed by copy for print_path() because it destroys the data in the parameter. It's one of the most powerful techniques in C++.

Answer 2

if you have how many lines you had printed you can use this macro
#define gotoxy(a,b) {COORD coord; coord.X=(b); coord.Y=(a) ; SetConsoleCursorPosition(GetStdHandle(STD_OUTPUT_HANDLE), coord);}
and go to that line and print " " for all characters you had printed.

Answer 3

It will make it easier if you do not print a newline after each line. Then you can go back and "erase" the text on the current line by outputting a number of "\b" (backspace) characters equal to the number of characters on the line, followed by the same number of spaces (to wipe out what was there). Then you can return to the beginning of the line by writing "\r" and write the whole line again.