I get _CrtIsValidHeapPointer(pUserData) error when running the code above.
Sometimes the code works perfectly, and sometimes this message appears. So I guess the problem is related to the memory allocation. But I've gone through the code many times and the numbers make sence to me (and also when debugging).
I noticed it happens in line "free(str_temp)" at the debugging.
The relevant code is here:
int main(){
int n;
int len;
char *str;
char command[3];
printf("Enter your string:\n");
scanf("%d", &n);
str = malloc(n+1);
scanf("%s", str);
while (1){
printf(">");
scanf("%s", command);
if (compare(command, "ml")) {
int k;
scanf("%d", &k);
multiply(str, n, k);
printf("Current string is %s\n", str);
n = ln(str);
continue;
}
free(str);
return 0;
}
void multiply(char *str, int n, int k) {
char *str_temp = malloc(n+1);
int i;
int j;
int q;
for (i = 0; i < n; i++){
str_temp[i] = str[i];
}
str_temp[n] = '\0';
free(str);
*str = malloc(n*k+1);
for (i = 0; i < k; i++){
for (j = 0; j < n; j++){
str[i*n + j] = str_temp[j];
}
}
str[n*k] = '\0';
free(str_temp);
}
Try to use message defination
void multiply(char **str, int n, int k)//Use **str(double pointer) instead of *str.
And call it like
multiply(&str, n, k);
Related
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 still dont know weather I am allowed discuss Competetive Programming Doubts here, please let me know..
Can someone help me on this SPOJ question, I am getting wrong Answer:
https://www.spoj.com/problems/SPIKES/
I have tried all the test cases I could think of and the code always gives correct output.
Before posting it here, I also asked it in spoj forum but Its been two days, no one replies...
#include<bits/stdc++.h>
using namespace std;
// # = 35
// # = 64
// . = 46
// s = 115
// Using Dijkstra to find the path with minimum no. of Spikes
int n,m,j;
const int N = 100;
const int INF = 9;
vector<int> g[N];
int vis[N][N];
pair<int,int> dist[N][N];
vector<pair<int,int>> movements = {
{0,1},{0,-1},{1,0},{-1,0}
};
bool isvalid(int i, int j){
return i>=0 && j>=0 && i<n && j<m;
}
void bfs(int sourcei, int sourcej){
set<pair<int,pair<int,int>>> q;
q.insert({0,{sourcei,sourcej}});
dist[sourcei][sourcej] = {0,INF};
while(q.size()>0){
auto curr_v = *q.begin();
int curr_i = (curr_v.second).first;
int curr_j = (curr_v.second).second;
int spikes = curr_v.first;
q.erase(q.begin());
if(vis[curr_i][curr_j]) continue;
vis[curr_i][curr_j] = 1;
for(auto m : movements){
int child_i = curr_i + m.first;
int child_j = curr_j + m.second;
int spikec = spikes;
if(!isvalid(child_i,child_j)) continue;
if(g[child_i][child_j] == 115) spikec = spikes+1;
if(vis[child_i][child_j]) continue;
if(g[child_i][child_j]==35) continue;
if(dist[child_i][child_j].second > spikec){
dist[child_i][child_j] = {(dist[curr_i][curr_j].first +1),spikec};
q.insert({spikec , {child_i,child_j}});
}
}
}
}
int main(){
cin>>n>>m>>j;
int start_j,start_i;
int end_j,end_i;
for (int i = 0; i < N; ++i){
for (int j = 0; j < N; ++j){
dist[i][j].second = INF;
dist[i][j].first = 0;
}
}
for (int i = 0; i < n; ++i){
for (int j = 0; j < m; ++j){
char x; cin>>x;
g[i].push_back((int)x);
if(x=='#') {
start_i = i;
start_j = j;
}
if(x=='x'){
end_i = i;
end_j = j;
}
}
}
bfs(start_i,start_j);
// for (int i = 0; i < n; ++i){
// for (int j = 0; j < m; ++j){
// cout<<dist[i][j].first<<","<<dist[i][j].second<<" ";
// }cout<<endl;
// }
if(dist[end_i][end_j].second <= (int)j/2) cout<<"SUCCESS"<<endl;
else cout<<"IMPOSSIBLE"<<endl;
return 0;
}
I need to make a c program that will make a histogram of all the letters present in a phrase the user gives. When I run it, I does it but gives a "* stack smashing detected *: terminated". Where would this error be coming from? (for ease right now I set max to 3). In the future i'll have it find the max
Thank you
Andrew
#include <stdio.h>
#include <ctype.h>
#include <string.h>
static void ReadText(int histo[26],int max) {
char phrase[100];
int i;
char Letter;
char toArray;
// read in phrase
printf("Enter Phrase: "); // reads in phrase with spaces between words
scanf("%[^\n]",phrase);
// count the number of certain letters that occur
for(i = 0; i <= strlen(phrase);++i) {
Letter = phrase[i];
if(isalpha(Letter) != 0){
Letter = tolower(Letter);
toArray = Letter - 97;
histo[(int)toArray] = histo[(int)toArray] + 1;
}
}
}
static void DrawHist(int histo[26], int max){
int i;
int j;
int histo2[50];
for(i = 0; i <= 26; i++) {
histo2[i+i] = histo[i];
if(i < 25) {
histo2[i+i+1] = 0;
}
}
// (i = 1; i <= 50; i++) {
// printf("%d",histo2[i]);
//}
//printf("\n");
for(i=max;i>0;--i) {
for(j=0;j<=51;++j) {
if((j < 51) && (histo2[j] >= i)) {
printf("|");
}
else if((j < 51) && (histo2[j] < i)){
printf(" ");
}
else if(j == 51){
printf("\n");
}
}
}
printf("+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-\n");
printf("A B C D E F G H I J K L M N O P Q R S T U V W X Y Z\n");
}
int main() {
int histo[26] = {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0};
int max = 3;
//int i;
ReadText(histo,max);
//for(i = 0; i<26;++i) {
// printf("%d",histo[i]);
//}
DrawHist(histo,max);
return 0;
}
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.