sometimes crashes

[jw]

//it sometimes crashes sometimes not why?
#include<iostream>
#include<fstream>
#include<vector>
#include<string>
#include<ctime>
using namespace std;
#ifndef NULL
#define NULL (short) 0
#endif

char
*words[53]={"come","garden","one","nice","go","we","some","where","old",
"days","who","bilir","where","school","eat","apple","look","ayy","see","eye","haha",
"birds","fly","come", "me", "can","sugar","laugh","ss", "ad", "asad",
"digf","you",
"know", "burn","ah ahh","desk","ice", "look",
"hand","cry","blood","goes","war",
"loop","open","pass","throw","age","monkey","doom","hobaa"};

//*******************node class*******************
class node{
private:
string word;
node *next;
public:

node()
{
next=NULL;
}

friend class list;

void display()
{
cout<<word<<" ";
}
};

//*****************list class*********************
class list{
private:
node *head,*tail,*TOP;
void append(node *new_node);

public:
list()
{
TOP=new node;
head=tail=TOP;
TOP->next=NULL;
}

~list()
{
node *ptr=head;
while(ptr)
{
node *tmp=ptr;
ptr=ptr->next;
delete tmp;

}
head=tail=TOP=NULL;

}


void getWords();
void displayAll();

};


void list::displayAll()
{

node *py;

py=head;

if(py==NULL)
{
cout<<"nothing to show"<<endl;
}
while(py!=NULL)
{//while py points sth reasonable
py->display();
py=py->next;
}

}

void list::append(node *ptr){

if(TOP->next==NULL)//first element
{ TOP->next=ptr;
head=ptr;
tail=ptr;
}
else
{

tail->next=ptr;
tail=ptr;

}

}

void list::getWords()
{ int num;
srand((unsigned)time( NULL ));
for(int m=0;m<50;m++)
{

num=(rand()%53);
node *object;
object=new node;
object->word=words[num];
append(object);
}
}




void main()
{
list thelist;
thelist.getWords();
thelist.displayAll();
}

 

[Victor Bazarov]

//it sometimes crashes sometimes not why?
[...]

Who's to tell?

Have you tried using the debugger? If yes, where does it crash? If you
haven't, why not?

BTW, you'd be much better off without hard-coding the number of your
words array as "53" but instead using '(sizeof words / sizeof *words)'.
You probably run into a wrong index you get from the rand() % 53. Are
you sure you have exactly 53 words?

V

 

[Axter]

//it sometimes crashes sometimes not why?
#include<iostream>
#include<fstream>
#include<vector>
#include<string>
#include<ctime>
using namespace std;
#ifndef NULL
#define NULL (short) 0
#endif

char
*words[53]={"come","garden","one","nice","go","we","some","where","old",
"days","who","bilir","where","school","eat","apple","look","ayy","see","eye","haha",
"birds","fly","come", "me", "can","sugar","laugh","ss", "ad", "asad",
"digf","you",
"know", "burn","ah ahh","desk","ice", "look",
"hand","cry","blood","goes","war",
"loop","open","pass","throw","age","monkey","doom","hobaa"};

//*******************node class*******************
class node{
private:
string word;
node *next;
public:

node()
{
next=NULL;
}

friend class list;

void display()
{
cout<<word<<" ";
}
};

//*****************list class*********************
class list{
private:
node *head,*tail,*TOP;
void append(node *new_node);

public:
list()
{
TOP=new node;
head=tail=TOP;
TOP->next=NULL;
}

~list()
{
node *ptr=head;
while(ptr)
{
node *tmp=ptr;
ptr=ptr->next;
delete tmp;

}
head=tail=TOP=NULL;

}


void getWords();
void displayAll();

};


void list::displayAll()
{

node *py;

py=head;

if(py==NULL)
{
cout<<"nothing to show"<<endl;
}
while(py!=NULL)
{//while py points sth reasonable
py->display();
py=py->next;
}

}

void list::append(node *ptr){

if(TOP->next==NULL)//first element
{ TOP->next=ptr;
head=ptr;
tail=ptr;
}
else
{

tail->next=ptr;
tail=ptr;

}

}

void list::getWords()
{ int num;
srand((unsigned)time( NULL ));
for(int m=0;m<50;m++)
{

num=(rand()%53);
node *object;
object=new node;
object->word=words[num];
append(object);
}
}




void main()
{
list thelist;
thelist.getWords();
thelist.displayAll();
}

You don't have 53 words in your list, so any time it points to the 53
pointer, it will be pointing to random memory.
You should avoid using pointers as much as possible. They're not safe,
and can lead to this type of bug that is hard to track down.
The following would require a little bit more memory, but would be
safer and easier to maintain:
const char
words[][22]={"come","garden","one","nice","go","we","some","where","old",

"days","who","bilir","where","school","eat","apple","look","ayy","see","eye­","haha",

"birds","fly","come", "me", "can","sugar","laugh","ss", "ad", "asad",
"digf","you",
"know", "burn","ah ahh","desk","ice", "look",
"hand","cry","blood","goes","war",
"loop","open","pass","throw","age","monkey","doom","hobaa"};

void list::getWords()
{
int num;
srand((unsigned)time( NULL ));
for(int m=0;m<50;m++)
{
const int MaxNum = sizeof(words) / sizeof(words[0]);
num=(rand()%MaxNum);

 

[Howard]

//it sometimes crashes sometimes not why?
#include<iostream>
#include<fstream>
#include<vector>
#include<string>
#include<ctime>
using namespace std;
#ifndef NULL
#define NULL (short) 0
#endif

char
*words[53]={"come","garden","one","nice","go","we","some","where","old",
"days","who","bilir","where","school","eat","apple","look","ayy","see","eye","haha",
"birds","fly","come", "me", "can","sugar","laugh","ss", "ad", "asad",
"digf","you",
"know", "burn","ah ahh","desk","ice", "look",
"hand","cry","blood","goes","war",
"loop","open","pass","throw","age","monkey","doom","hobaa"};

I count only 52 words specified there.

What happens when you try to use the item at words[52]? Test it in your
debugger and find out.

(Perhaps you meant "ah ahh" to be two separate words?)

-Howard

 

[Kai-Uwe Bux]

//it sometimes crashes sometimes not why?
#include<iostream>
#include<fstream>
#include<vector>
#include<string>
#include<ctime>
using namespace std;
#ifndef NULL
#define NULL (short) 0
#endif

char
*words[53]={"come","garden","one","nice","go","we","some","where","old",
"days","who","bilir","where","school","eat","apple","look","ayy","see","eye","haha",
"birds","fly","come", "me", "can","sugar","laugh","ss", "ad", "asad",
"digf","you",
"know", "burn","ah ahh","desk","ice", "look",
"hand","cry","blood","goes","war",
"loop","open","pass","throw","age","monkey","doom","hobaa"};

Count! This list has only 52 elements. Thus word[52] is uninitialized.

[snip]


Best

Kai-Uwe Bux

 

[Victor Bazarov]

jw wrote:

//it sometimes crashes sometimes not why?
#include<iostream>
#include<fstream>
#include<vector>
#include<string>
#include<ctime>
using namespace std;
#ifndef NULL
#define NULL (short) 0
#endif

char
*words[53]={"come","garden","one","nice","go","we","some","where","old",

"days","who","bilir","where","school","eat","apple","look","ayy","see","eye","haha",

"birds","fly","come", "me", "can","sugar","laugh","ss", "ad", "asad",
"digf","you",
"know", "burn","ah ahh","desk","ice", "look",
"hand","cry","blood","goes","war",
"loop","open","pass","throw","age","monkey","doom","hobaa"};

Count! This list has only 52 elements. Thus word[52] is uninitialized.

No, it's not uninitialised, it's initialised to 0.

V

 

[Axter]

//it sometimes crashes sometimes not why?
#include<iostream>
#include<fstream>
#include<vector>
#include<string>
#include<ctime>
using namespace std;
#ifndef NULL
#define NULL (short) 0
#endif

char
*words[53]={"come","garden","one","nice","go","we","some","where","old",
"days","who","bilir","where","school","eat","apple","look","ayy","see","eye","haha",
"birds","fly","come", "me", "can","sugar","laugh","ss", "ad", "asad",
"digf","you",
"know", "burn","ah ahh","desk","ice", "look",
"hand","cry","blood","goes","war",
"loop","open","pass","throw","age","monkey","doom","hobaa"};

//*******************node class*******************
class node{
private:
string word;
node *next;
public:

node()
{
next=NULL;
}

friend class list;

void display()
{
cout<<word<<" ";
}
};

//*****************list class*********************
class list{
private:
node *head,*tail,*TOP;
void append(node *new_node);

public:
list()
{
TOP=new node;
head=tail=TOP;
TOP->next=NULL;
}

~list()
{
node *ptr=head;
while(ptr)
{
node *tmp=ptr;
ptr=ptr->next;
delete tmp;

}
head=tail=TOP=NULL;

}


void getWords();
void displayAll();

};


void list::displayAll()
{

node *py;

py=head;

if(py==NULL)
{
cout<<"nothing to show"<<endl;
}
while(py!=NULL)
{//while py points sth reasonable
py->display();
py=py->next;
}

}

void list::append(node *ptr){

if(TOP->next==NULL)//first element
{ TOP->next=ptr;
head=ptr;
tail=ptr;
}
else
{

tail->next=ptr;
tail=ptr;

}

}

void list::getWords()
{ int num;
srand((unsigned)time( NULL ));
for(int m=0;m<50;m++)
{

num=(rand()%53);
node *object;
object=new node;
object->word=words[num];
append(object);
}
}




void main()
{
list thelist;
thelist.getWords();
thelist.displayAll();
}

You don't have 53 words in your list, so any time it points to the 53
pointer, it will be pointing to random memory.
You should avoid using pointers as much as possible. They're not safe,
and can lead to this type of bug that is hard to track down.
The following would require a little bit more memory, but would be
safer and easier to maintain:
const char
words[][22]={"come","garden","one","nice","go","we","some","where","old",

"days","who","bilir","where","school","eat","apple","look","ayy","see","eye­","haha",

"birds","fly","come", "me", "can","sugar","laugh","ss", "ad", "asad",
"digf","you",
"know", "burn","ah ahh","desk","ice", "look",
"hand","cry","blood","goes","war",
"loop","open","pass","throw","age","monkey","doom","hobaa"};

void list::getWords()
{
int num;
srand((unsigned)time( NULL ));
for(int m=0;m<50;m++)
{
const int MaxNum = sizeof(words) / sizeof(words[0]);
num=(rand()%MaxNum);

I forgot to mention that you should also move your seed (srand) to your
main function.
Otherwise, you'll find you're not getting true random numbers.
Typically, you only want to perform the seed once in your application.

 

[Old Wolf]

//it sometimes crashes sometimes not why?
char
*words[53]={"come","garden","one","nice","go","we","some","where","old",
"days","who","bilir","where","school","eat","apple","look","ayy","see","eye","haha",
"birds","fly","come", "me", "can","sugar","laugh","ss", "ad", "asad",
"digf","you",
"know", "burn","ah ahh","desk","ice", "look",
"hand","cry","blood","goes","war",
"loop","open","pass","throw","age","monkey","doom","hobaa"};

You don't have 53 words in your list, so any time it points to the 53
pointer, it will be pointing to random memory.

Actually it will be a null pointer. Initializing a struct or array
always
initializes all members. If there are fewer initializers than members,
the other members are initialized with { 0 } .