"this" C++

[YourMomsASmurph]

Well it seems that I have no idea how "this" is supposed to work.

My compiler gives me:


/home/fr0gg3r/workspace/Falling Block Game/Blocks.h||In constructor ‘block::block(int)’:|
/home/fr0gg3r/workspace/Falling Block Game/Blocks.h|28|error: request for member ‘spawnBlock’ in ‘this’, which is of non-class type ‘block* const’|


So, I have a

class block, and within the class is a method called

spawnBlock(int spwn) The job of the spawnBlock method is to initialize the main variable of the block class.

std::vector<coord> blockVert with a random block. (tetris block)

The error is occuring when I try to use the constructor

block::block(int spwn){
this.spawnBlock(spwn);
}


To give context here is the code that goes with it Note::It has a lot of errors apparently, but until I can figure out how to use "this" i cant fix any of them.



#ifndef BLOCK_H
#define BLOCK_H

#include <vector>
#include "co-ords.h"
#include "gameMap.h"

class block {
private:
std::vector<coord> blockVert;

public:
block(); //Constructor
block(int spwn);

void spawnBlock(int spwn);
void move(char dir);
void rotate();
bool collision(char dir, gameMap map);
void printBlock();
};

/*Constructor*/
block::block() {
//does nothing ( blockVert stays as null until a block is spawned)
}
block::block(int spwn){
this.spawnBlock(spwn);
}
/*End of Constructors*/

void block::spawnBlock(int spwn) {

blockVert.erase(blockVert.begin(), blockVert.size()); // removes blocks in the vector.

int block(0);

if (spwn != 0) {
block = spwn;
} else {
block = ((rand() % 8) + 1);
}

switch (block) {

case 1:
this.blockVert.push_back(coord(0,1));
this.blockVert.push_back(coord(0,0));
this.blockVert.push_back(coord(0,1));
this.blockVert.push_back(coord(0,2));
this.blockVert.push_back(coord(0,3));
break;
case 2:
this.blockVert.push_back(coord(0,1));
this.blockVert.push_back(coord(0,0));
this.blockVert.push_back(coord(1,0));
this.blockVert.push_back(coord(0,1));
this.blockVert.push_back(coord(0,2));
break;
case 3:
this.blockVert.push_back(coord(0,1));
this.blockVert.push_back(coord(0,0));
this.blockVert.push_back(coord(0,1));
this.blockVert.push_back(coord(0,2));
this.blockVert.push_back(coord(1,2));
break;
case 4:
this.blockVert.push_back(coord(0,0));
this.blockVert.push_back(coord(0,1));
this.blockVert.push_back(coord(1,0));
this.blockVert.push_back(coord(1,1));
break;
case 5:
this.blockVert.push_back(coord(1,1));
this.blockVert.push_back(coord(1,1));
this.blockVert.push_back(coord(0,1));
this.blockVert.push_back(coord(1,0));
this.blockVert.push_back(coord(2,0));
break;
case 6:
this.blockVert.push_back(coord(1,1));
this.blockVert.push_back(coord(1,1));
this.blockVert.push_back(coord(1,0));
this.blockVert.push_back(coord(0,1));
this.blockVert.push_back(coord(2,1));
break;
case 7:
this.blockVert.push_back(coord(1,1));
this.blockVert.push_back(coord(1,1));
this.blockVert.push_back(coord(0,0));
this.blockVert.push_back(coord(0,1));
this.blockVert.push_back(coord(2,1));
break;
default:
this.blockVert.push_back(coord(0,1));
this.blockVert.push_back(coord(0,1));
this.blockVert.push_back(coord(0,2));
this.blockVert.push_back(coord(0,0));
this.blockVert.push_back(coord(0,3));
break;
}

}

void block::move(char dir) {

if (dir == 'D'){
for (int i = blockVert.size()-1 ; i >= 0; i--) {
blockVert[i] - coord(0,1);
}

}

if (dir == 'L'){
for (int i = blockVert.size()-1 ; i >= 0; i--) {
blockVert[i] - coord(1,0);
}

}

if (dir == 'R'){
for (int i = blockVert.size()-1 ; i >= 0; i--) {
blockVert[i] + coord(1,0);
}

}

}
void block::rotate() {
coord tmpVert;
std::vector<coord> square;

square.push_back(coord(0,0));
square.push_back(coord(0,1));
square.push_back(coord(1,0));
square.push_back(coord(1,1));



if (square != blockVert) { // dont try to rotate a square. //

//For -90 degree turn (90 degrees to the right) we subtract rotating point by the pivot point. then multiply by rotation hen { 0 , -1 }
//which gives us that P after rotation is [ P(x0,y0) - Piv(x,y) ] = Q(a,b) then new point is (-b,a) + Piv(x,y) { 1 , 0 }
for (int i = blockVert.size() - 1 ; i > 0 ; i--) {
tmpVert = blockVert[i] - blockVert[0];
tmpVert = tmpVert.rotate();
blockVert[i] = tmpVert + blockVert[0];
}
}

}
bool block::collision(char dir, gameMap map) {
int xInvert(0);

if (dir == 'L')
xInvert = -1;
if (dir == 'R')
xInvert = 1;

for (int i = blockVert.size() ; i > 0 ; i--) {
if (map.blockExists(blockVert[i].getX() + xInvert, blockVert[i].getY() + 1)) { //xinvert tells it to check one block left (-1), or one block right.(+1)
return true;
} else
return false;


}

}

void printBlock() {
for (int i = blockVert.size() ; i > 0 ; i-- ) {
std::cout << blockVert[i].getX() <<"," << blockVert[i].getY() <<"\n";
}

}

#endif

[dwhitney67]

I feel like it's Groundhog Day.

"this" is a pointer; you are not using it as such. Try


block::block(int spwn){
this->spawnBlock(spwn);

// or if you want to type even more...

(*this).spawnBlock(spwn);

// or just keep things simple...

spawnBlock(spwn);
}

Why are you using "this" anyhow? Are you trying to impress someone with your ability to type extra characters?

[YourMomsASmurph]

Using "this" because the code was downright failing before, and at the time i thought it might help. Apparently it didn't; especially considering that I don't know how to use it. Then I remove it again, and the code works all of a sudden, with the exception of a couple errors, its kind of weird.