My screen isn't printing please help me with this.I'm a beginner and i'm trying to make snake game.
void myScreen()
{
char screen[30][50];
int x = 30, y = 50;
for (int i = 1; i <= x; i++)
{
if (i == 1 || i == x)
for (int j = 1; j <= y; j++)
screen[i][j] = '#';
else
for (int j = 1; j <= y; j++)
if (j == 1 || j == y)
screen[i][j] = '#';
else
screen[i][j] = ' ';
}
for (int i = 1; i <= x; i++)
{
for (int j = 1; j <= y; j++)
cout << screen[i][j];
cout << endl;
}
}
the screen isn't printing
C++ arrays are zero-based. That means that the "first" element has actually the index 0. So your code like that:
for(int i=1;i<=x;i++)
shall be reworked like that:
for (int i = 0; i < x; i++)
Now back to your question: why it isn't printing? The fact is that you are accessing the memory outside of the array, and that is an Undefined Behavior in C++. That may be observed as the program that never gets to the code that prints the array.
The reason it becose you don't call the funtion in main()
here how to do it:
int main(){
myScreen();
}
the int main() is when the program is starting.after you can call other functions
They have other reason like you don't import any libraries
#include <iostream>
using namespace std;
add this in the start of your code
You are missing a main function in your code. In C++ (and C), the main function gets called when you start the program. All other functions that you want to be executed you have to call from this function. Additionally, you start counting your array indexes from 1 - but the first element of an array has 0 as index in most programming languages (including C, C++, Python, JavaScript, bash, …, …). This code should work:
#inclue <iostream>
using namespace std;
void myScreen()
{
int x = 30, y = 50;
char screen[x][y];
for (int i = 0; i < x; i++)
{
if (i == 0 || i == x - 1)
{
for (int j = 0; j < y; j++)
{
screen[i][j] = '#';
}
} else
{
for (int j = 0; j < y; j++)
{
if (j == 1 || j == y)
{
screen[i][j] = '#';
} else
{
screen[i][j] = ' ';
}
}
}
}
for (int i = 0; i < x; i++)
{
for (int j = 0; j < y; j++)
{
cout << screen[i][j];
}
cout << endl;
}
}
int main(int argc, char* argv[]) {
myScreen();
}
Related
Alright so I have created this code. However, when i run it, it stops when it displays 104 for the counter??? I am so frustrated because I don't know how this could happen. The purpose of the code is to do the typical magic number output where the rows all add up to the same thing, the columns all add up to the same thing, and the diaganols all add up to the same thing. I believe the functions to do these calculations are correct, but the counter keeps stopping short of the 10000 attempts I am trying to do.
#include <iostream>
#include<time.h>
#include<stdlib.h>
using namespace std;
void getrandom();
void insertnumber(int n);
bool magic();
void create();
const int rows = 3;
const int cols = 3;
int arr[rows][cols] = { {0,0,0}, {0,0,0} , {0,0,0} };
int main() {
int counter = 0;
do
{
counter++;
cout << counter << endl;
getrandom();
if (counter == 100000)
break;
} while (!magic());
create();
cout << "It took " << counter << " tries." << endl;
return 0;
}
void getrandom() {
int n = 0;
const int size = 9;
int oldnum[size];
for (int i = 0; i < rows * cols; i++) {
oldnum[i] = 0;
}
srand(time(NULL)); // had to import the new libraries to use this
bool used = true;
for (int i = 0; i < size; i++) {
do
{
used = true;
n = rand() % 9 + 1;
if (oldnum[n - 1] == 0)
{
oldnum[n - 1] = n;
used = false;
}
} while (used);
insertnumber(n);
}
}
void insertnumber(int n) {
for (int i = 0; i < rows; i++) {
for (int j = 0; i < cols; j++) {
if (arr[i][j] == 0) {
arr[i][j] = n;
return;
}
}
}
}
bool magic() {
int rowsum = arr[0][0] + arr[0][1] + arr[0][2];
for (int i = 1; i < cols; i++)
{
if (arr[i][0] + arr[i][1] + arr[i][2] != rowsum)
return false;
}
for (int j = 0; j < rows; j++)
{
if (arr[0][j] + arr[1][j] + arr[2][j] != rowsum)
return false;
}
if (arr[0][0] + arr[1][1] + arr[2][2] != rowsum)
return false;
if (arr[0][2] + arr[1][1] + arr[2][0] != rowsum)
return false;
return true;
}
void create() {
{
for (int i = 0; i < rows; i++) {
for (int j = 0; i < cols; j++) {
cout << arr[i][j] << " ";
}
cout << endl;
}
}
}
You can try using a debugger for such problems.
I think you code crashes because of this:
for (int i = 0; i < rows; i++) {
for (int j = 0; i < cols; j++) {
It looks like you mean j < cols here :)
Check line 76. When I compile and run the code, line 76 is where the exception is thrown.
This line specifically
arr[i][j] = n;
It seems your insertnumber() function is the culprit.
I'm writing a program that is made of a function that takes in a 2d array, c0unts the evens in the array and returns the amount of evens in that array. The function isn't returning the value that i intend it to, which is 6. Sometimes I get 0, sometimes I get a number like 2147483646.
#include <iostream>
#include <array>
using namespace std;
const int MaxNumOfRows = 3;
const int MaxNumOfColumns = 2;
int Even(int A[MaxNumOfRows][MaxNumOfColumns], int length, int width)
{
int NumnberOfEvens = 0;
int i;
int j;
for (i = 0; i < length; length++)
{
for (j = 0; j < width; width++)
{
if (A[i][j] % 2 == 0)
{
NumnberOfEvens++;
}
}
}
return NumnberOfEvens;
}
int main()
{
//int output = 0;
int A[MaxNumOfRows][MaxNumOfColumns] =
{
{2,2},{2,4},{2,2}
};
Even(A, MaxNumOfRows, MaxNumOfColumns);
//output = Even(A, MaxNumOfRows, MaxNumOfColumns);
cout << Even(A, MaxNumOfRows, MaxNumOfColumns) << endl;
system("pause");
return 0;
}
Check those for loops, I imagine you want to be incrementing the variables ++i and ++j rather than width++ and length++.
With an example this trivial, I imagine stepping through the executing code and finding the problem in a debugger would be pretty straightforward...are you writing this using an IDE with a debugger?
You are not applying increment on loop variables ('i' and 'j') here. 'length' and 'width' are increasing (due to length++, width++) whereas 'i' and 'j' are not. So, loop won't stop and thus the garbage values.
for (i = 0; i < length; length++)
{
for (j = 0; j < width; width++)
{
if (A[i][j] % 2 == 0)
{
NumnberOfEvens++;
}
}
}
This must work.
for (i = 0; i < length; i++)
{
for (j = 0; j < width; j++)
{
if (A[i][j] % 2 == 0)
{
NumnberOfEvens++;
}
}
}
I am currently working on a program that prints a 5 variable truth table. I am using a 2d array. My code currently produces the table, but says it is corrupt and "the stack around the variable "table" was corrupted. Any help?
#include <iostream>
using namespace std;
int main() {
bool table[5][32];
for (int i = 0; i < 32; i++) {
for (int j = 0; j < 5; j++) {
table[i][j] = ((i >> j)& 1);
}
}
for (int i = 0; i < 32; i++) {
for (int j = 0; j < 5; j++) {
cout << table[i][j] << " ";
}
cout << endl;
}
return 0;
}
This is homework, so I would like to understand it, not just have an answer.
The index is wrong. Only table[0] to table[4] are available, so accessing table[5] to table[31] is illegal.
Try this:
#include <iostream>
using namespace std;
int main() {
bool table[32][5]; // swap 32 and 5
for (int i = 0; i < 32; i++) {
for (int j = 0; j < 5; j++) {
table[i][j] = ((i >> j)& 1);
}
}
for (int i = 0; i < 32; i++) {
for (int j = 0; j < 5; j++) {
cout << table[i][j] << " ";
}
cout << endl;
}
return 0;
}
There is attempt to read out of bound values from array.
If you need 5x32 matrix Use code below:
for (int i = 0; i < 5; i++) { // 32-> 5
for (int j = 0; j < 32; j++) { // 5->32
If you need 32x5 matrix then replace code below:
bool table[32][5]; //it was table[5][32];
New to c++. I'm getting the "out of range" error message when try to debug the code. I tried to used resize(), but it is still not fixed. The code is to read instructions into a 2d vector and print out the graph.
What am I doing wrong?
#include<iostream>
#include<fstream>
#include<vector>
#include<string>
#include<sstream>
using namespace std;
typedef struct Pattern{
int rowNum;
int colNum;
char token;
bool isTriangular;
bool isOuter;
}Pattern;
void CommandProcessing(vector<string>&, Pattern&);
void Builder(Pattern&, vector<vector<char>>&);
void Printer(vector<vector<char>>&);
int main()
{
Pattern characters;
vector<vector<char>> key;
characters.colNum = 3;
characters.rowNum = 3;
characters.token = '#';
characters.isOuter = false;
characters.isTriangular = false;
Builder(characters, key);
Printer(key);
}
void Builder(Pattern& character, vector<vector<char>>& matrix)
{
int i = 0, j = 0;
char c;
if (character.token == 0)
c = 'a';
else
c = character.token;
matrix.resize(character.rowNum);
for (int i = 0; i < character.rowNum; i++){
if (character.isTriangular)
matrix[i].resize(i + 1);
else
matrix[i].resize(character.colNum);
if (character.isOuter)
{
if (character.isTriangular)
{
if (i = j)
matrix[i][j] = c;
else
matrix[character.rowNum - 1][i] = matrix[i][0] = c;
}
else
matrix[0][j] = matrix[i][0] = matrix[character.rowNum - 1][j] = matrix[i][character.colNum - 1] = c;
i++;
j++;
}
else
{
if (character.isOuter)
{
while (i <= j){
for (i = 0; i < character.rowNum; i++)
for (j = 0; i < character.colNum; j++)
matrix[i][j] = c;
}
}
else
for (i = 0; i < character.rowNum; i++)
for (j = 0; i < character.colNum; j++)
matrix[i][j] = c;
}
c++;
}
}
void Printer(vector<vector<char>>& print)
{
for (int i = 0; i < print.size(); i++){
for (int j = 0; j < print[i].size(); j++)
{
cout << print[i][j] << endl;
}
}
}
if (i = j) should be if (i == j).
if (i = j) do a assignment and test if i != 0.
Other problems:
while (i <= j){
for (i = 0; i < character.rowNum; i++)
for (j = 0; i < character.colNum; j++) // You test `i` instead of j
matrix[i][j] = c;
// Once test fixed
// Here `i == character.rowNum` and `j == character.colNum` (if `character.rowNum != 0`)
// So the while loop condition doesn't change and may so do infinite loop
}
I am trying to output a 2D array with a border around it but for some odd reason I am not getting any output, just a blank space. I am pretty sure the problem is in the if statement but im not sure whats wrong.
#include <iostream>
#include "windows.h"
using namespace std;
//prototypes
void DisplayMap();
void SetBorder();
//global vars
const int H = 70;
const int W = 40;
char Map[H][W];
int main()
{
//system("cls");
DisplayMap();
SetBorder();
return 0;
}
void SetBorder(){
for(int i = 0; i < H; i++ ){
for(int j = 0; j < W; j++){
if(i == 0 || i == 69 || j == 0 || j == 39 ){ Map[i][j] = 'x';}
// else Map[i][j] = ' ';
}
}
}
void DisplayMap(){
for(int i = 0; i < H; i++ ){
for(int j = 0; j < W; j++){
cout << Map[i][j];
}
cout << "\n";
}
}
SetBorder();
DisplayMap();
Swap the function calls. You want to set the border characters first, then display the map.
You need to fill the Map first and then to display it:
int main()
{
//system("cls");
SetBorder();
DisplayMap();
return 0;
}