I'm trying to create a char matrix using dynamic allocation (char**). It represents a board where the margins are '#' character and in the middle is the ASCII 32 (blank space). When I run the code this massage appear: "Exception thrown at 0x00007FFD9ABF024E (ucrtbased.dll) in myapp.exe: 0xC0000005: Access violation reading location " in some cpp file.
Here's my code:
#include <iostream>
using namespace std;
char** allocateBoard(int n)
{
char** Board = 0;
Board = new char* [n+2];
int i;
for (i = 0; i < n + 2; i++)
{
Board[i] = new char[n * 2 + 2];
}
return Board;
}
void initBoard(char**& Board, int n)
{
int i, j;
for (i = 0; i < n; i++)
{
for (j = 0; j < n * 2; j++)
{
if (i == 0 || i == n - 1) Board[i][j] = '#';
else if (j == 0 || j == n * 2 - 1) Board[i][j] = '#';
else Board[i][j] = 32;
}
}
}
void showBoard(char** Board, int n)
{
int i, j;
for (i = 0; i < n; i++)
{
for (j = 0; j < n * 2; j++)
{
cout << Board[i][j];
}
cout << endl;
}
}
int main()
{
int n = 4;
char** Board = 0;
Board = allocateBoard(n);
initBoard(Board, n);
showBoard(Board, n);
cout << endl;
showBoard(Board, n);
for (int i = 0; i < n * 2 + 4; i++)
{
delete[] Board[i];
}
delete[] Board;
return 0;
}
Does anyone know where is the problem? As a very beginner I can't see where is the mistake. I've allocated more space in the matrix than I'm actually using so I can't figure why this message appears. Is the deallocation the problem?
Thanks!
I have implemented a quick sort algorithm in Dart which sorts a list of random integers in the range from 0 to 100. Most of the times, it throws a 'not in inclusive range' exception. Other times, it works. I don't understand what is wrong with my code or logic here.
import 'dart:math';
List<int> list = [];
void main() {
randomize();
quickSort(0, list.length - 1);
print(list);
}
void randomize() {
for (int i = 0; i < 100; ++i) {
list.add(Random().nextInt(100));
}
}
void quickSort(int l, int h) {
if (l < h) {
int mid = partition(l, h);
quickSort(l, mid - 1);
quickSort(mid + 1, h);
}
}
int partition(int l, int h) {
int pivot = l;
int i = l;
int j = h;
while (i < j) {
while (list[i] <= list[pivot]) {
++i;
}
while (list[j] > list[pivot]) {
--j;
}
if (i < j) {
int temp = list[i];
list[i] = list[j];
list[j] = temp;
}
}
int temp = list[pivot];
list[pivot] = list[j];
list[j] = temp;
return j;
}
I wrote a code to print the length of the longest line from my input and print out as much as possible of the longest line(There is a maximum length of what I can output the longest line). But I got this error. I tried everything I could yet still no clue. Is there anyone who might help?
#include<stdio.h>
#define MAXLINE 10
int getline(char line[], int len) {
int i,c,max;
i = 0;
max = 0;
while ((c = getchar()) != EOF&&c!='\n') {
if (i < len) {
line[i] = c;
}
i += 1;
}
if (i < len) {
if (c == '\n') {
line[i] = c;
i += 1;
}
line[i] = '\0';
}
else if (i >= len) {
line[len] = '\0';
}
return i;
}
void copy(char from[], char to[]) {
int i = 0;
while (from[i] != '\0') {
to[i] = from[i];
i += 1;
}
to[i] = '\0';
}
main() {
char longline[MAXLINE];
char longestline[MAXLINE];
char maxlong[MAXLINE];
int length;
int max = 0;
int maxline = 0;
while ((length = getline(longline, MAXLINE)) > 0) {
if (length > max && length < MAXLINE) {
copy(longline, longestline);
max = length;
}
else if (length > MAXLINE) {
if (length > maxline) {
maxline = length;
copy(longline, maxlong);
}
}
}
if (maxline == 0) {
printf("%s", longestline);
}
else {
printf("%s\n%d\n", maxlong, maxline);
}
}
Could anyone please help me understand why Clang reallocates the same memory address for different variables while their lifetimes intersect?
I am using a sample program (below) to show the problem.
When I compile the program with clang -O0, variable j in function ok has the same memory address as variable solutions in function nqueens.
Function ok is called inside function nqueens, which means that the lifetime of the variables intersect; the same stack space cannot be used/reused for both functions.
Compiling the program with gcc or clang at -O1, however, they are assigned different memory addresses.
Any help is appreciated!
#include <stdlib.h>
#include <stdio.h>
#include <memory.h>
#include <alloca.h>
/* Checking information */
static int solutions[] = {
1,
0,
0,
2,
10, /* 5 */
4,
40,
92,
352,
724, /* 10 */
2680,
14200,
73712,
365596,
};
#define MAX_SOLUTIONS sizeof(solutions)/sizeof(int)
int total_count;
int sharedVar = 0;
int ok(int n, char *a)
{
int i, j;
char p, q;
printf("jjjjjjjjj: %d, %p\n", n,&j);
for (i = 0; i < n; i++) {
p = a[i];
for (j = i + 1; j < n; j++) {
q = a[j];
if (q == p || q == p - (j - i) || q == p + (j - i))
return 0;
}
}
return 1;
}
void nqueens (int n, int j, char *a, int *solutions)
{
int i,res;
sharedVar = sharedVar * j - n;
if (n == j) {
/* good solution, count it */
*solutions = 1;
return;
}
printf("solutions: %d, %p\n", j, &solutions);
*solutions = 0;
/* try each possible position for queen <j> */
for (i = 0; i < n; i++) {
a[j] = (char) i;
if (ok(j + 1, a)) {
nqueens(n, j + 1, a,&res);
*solutions += res;
}
}
}
int main()
{
int size = 3;
char *a;
// printf("total_count: %p\n", &total_count);
total_count=0;
a = (char *)alloca(size * sizeof(char));
printf("Computing N-Queens algorithm (n=%d) ", size);
sharedVar = -5;
nqueens(size, 0, a, &total_count);
printf("completed!\n");
printf("sharedVar: %d\n", sharedVar);
}
I was trying to solve this problem - link. Segment Tree with Lazy Propagation. But I dont know where I made mistake. Please help me find the bug.
I am new to Segment Tree with Lazy Propagation. But my code seems ok.
#include <bits/stdc++.h>
using namespace std;
const int MAXN = 100000;
struct info{ long long sum, prop; }; info tree[300010];
void update(int node, int l, int r, int i, int j, int val) {
if( i > r || j < l) return;
if(i <= l && j >= r) {
tree[node].sum += (r-l+1)*val;
tree[node].prop += val;
return;
} int left = node*2, right = left|1, mid = (l+r)/2;
update(left, l, mid, i,j,val);
update(right, mid+1, r, i,j,val);
tree[node].sum = tree[left].sum + tree[right].sum + (r-l+1)*tree[node].prop;
}
long long query(int node, int l, int r, int i, int j, long long carry = 0) {
if(i > r || j < l ) return 0;
if(i <= l && j >= r) return tree[node].sum + (r-l+1)*carry;
int mid = (l+r)/2, left = node*2, right = left|1;
long long ret = query(left, l, mid, i,j, carry + tree[node].prop);
ret += query(right,mid+1,r,i,j, carry + tree[node].prop);
return ret;
}
int main(int argc, char const *argv[]) {
#ifndef ONLINE_JUDGE
freopen("in", "r", stdin);
#endif
int t,co=0; scanf("%d", &t); while(t--) {
int n, q; scanf("%d %d", &n, &q);
for(int i=0; i<=3*n; i++) tree[i].sum = tree[i].prop = 0;
printf("Case %d:\n", ++co);
while(q--) {
int type,a,b,c; scanf("%d", &type); if(!type) {
scanf("%d %d %d", &a, &b, &c);
update(1, 0, n-1, a,b,c);
} else {
scanf("%d %d", &a, &b);
printf("%d\n", query(1, 0, n-1, a,b));
}
}
}
}
First of all this site is not for finding bug in code. Try https://codereview.stackexchange.com/ for this purpose.
Anyway In your code return type of function query() is long long but in main you are printing integer type. change printf("%d\n", query(1, 0, n-1, a,b)); to printf("%lld\n", query(1, 0, n-1, a,b)); and I hope you will get AC.