Can some one tell me what is wrong in the for loop? When I run it, it interrupts. I tried to debug to see what is wrong, I noticed that in the for loop it just stops:
#define MAX_POPULATION 64
float **tr_pop;//Tournament candidates
float **matingPool;//Mating pool
tr_pop=new float *[m];
matingPool=new float *[m];
for(l=0;l<m+1;l++)//allocating
{
tr_pop[l]=new float[MAX_POPULATION];
matingPool[l]=new float[MAX_POPULATION];
}
for ( int r = 0; r < row; ++r )//deleting
{
delete [] matingPool[r];//Stops here (not ending program just frozen)
delete [] tr_pop[r];
}
delete [] tr_pop;
delete [] matingPool;
=======OK. PROBLEM SOLVED=======
Here is the reason:
I just changed the MAX_POPULATION into the MAX_POPULATION+1 and it worked.
for(l=0;l<m+1;l++)
{
tr_pop[l]=new float[MAX_POPULATION+1];
matingPool[l]=new float[MAX_POPULATION+1];
}
Because in another function I think I was doing violation:
void crossover()
{
int p1,p2,i,j;float tempBit;
p1=m/3;
p2=(2*m)/3;
for(j=0;j<MAX_POPULATION;j++)
{
for(i=p1;i<p2;i++)
{
tempBit=matingPool[i][j];
matingPool[i][j]=matingPool[i][j+1];//THE VIOLATION POINT (I THINK)
matingPool[i][j+1]=tempBit;
}
j++;
}
As you can see, when j = MAX_POPULATION at the end of the loop, i was trying to reach MAX_POPULATION + 1. So I changed the allocations for columns, and the problem solved :)
You're running into undefined behavior:
for(l=0;l<m+1;l++)//allocating
{
tr_pop[l]=new float[MAX_POPULATION];
}
should be
for(l=0;l<m;l++)//allocating
{
tr_pop[l]=new float[MAX_POPULATION];
}
You're allocating m elements for each of the arrays and try to access m+1.
You are allocating m float* but in for loop you are iterating from 0..m while allocating memory, it should from 0..m-1. For that you need to chnage the for loop to : for(l=0;l<m;l++).
Related
Well, I have a class which is supposed to be a container for quadratic polynomials (which is a template and I'm using floats there, but that shouldn't matter much). I made it using a dynamic array, and I was supposed to overload + and - operators... Not a problem, eh? Well, it seemed all nice and dandy until I actually run it.
listf listf::operator+(listf rhs)
{
listf newlist;
for(int i = 0; i < elementcount; ++i)
newlist.add(array[i]);
for(int j = 0; j < rhs.elementcount; ++j)
newlist.add(rhs.array[j]);
std::cout<<newlist;
return newlist;
}
Nothing much. Should do its job correctly, right? That cout is just to check if it works. But it does not.
Should do something like this, right?
With one list consisting of:
X^2+5x+52.4
2X^2+7x-12
and the second one having just X^2+2X+1, it should make a list and display:
X^2+5x+52.4
2X^2+7x-12
X^2+2X+1
Buuuut no, it comes to this:
-1.5584e+038X^2-1.5584e+038x-1.5584e+038
-1.5584e+038X^2-1.5584e+038x-1.5584e+038
-1.5584e+038X^2-1.5584e+038x-1.5584e+038
I've been battling with it for quite some time and have not found why it would do that.
Code for adding new polynomials is still quite simple:
void listf::add(polynomial<float> plnm)
{
if(array == NULL)
{
++elementcount;
array = new polynomial<float>[elementcount];
array[0] = plnm;
}
else
{
array = resize(array, elementcount+1, elementcount);
array[elementcount++] = plnm;
}
}
And resize is a private function in this class:
polynomial<float>* listf::resize(polynomial<float>* arr, int newSize, int oldSize)
{
polynomial<float>* newArr = new polynomial<float>[newSize];
for(int i = 0; i < oldSize; ++i)
{
newArr[i] = arr[i];
}
delete[] arr;
return newArr;
}
If we're making a smaller array (for deleting objects), I just put oldSize equal to newSize (I know it's a bad practice and confusing for others, but I was just testing things :( )
I'm out of ideas. Adding new elements to an object seems working, but when I want to add two objects it breaks, prints elements that are not correct and then crashes with CodeLite reporting something like "ntdll!LdrVerifyImageMatchesChecksumEx" in Call Stack. Even better, when I tested it right now, it displayed correct values, but still crashed at return.
Forget the home-made dynamic array and use vector. Whenever you go into the realm of classes and memory management, it isn't as trivial as coding up a few new[] and delete[] calls. It can stop you dead in your tracks in the development of your program.
#include <vector>
//...
typedef std::vector<polynomial<float> > PolynomialFloatArray;
//...
class listf
{
PolynomialFloatArray array;
//...
void add(const polynomial<float>& plnm);
//...
PolynomialFloatArray& resize(PolynomialFloatArray& arr, int newSize)
};
//...
void listf::add(const polynomial<float>& plnm)
{
array.push_back(plnm);
}
PolynomialFloatArray& listf::resize(PolynomialFloatArray& arr, int newSize)
{
arr.resize(newSize);
return arr;
}
There in a nutshell is all of that code you wrote, reduced down to 2 or 3 lines.
Like the comments on the question point out, you would probably be better off using std::vector for this, as it has push_back() to add stuff to the end, and automatically resizes itself to do so, though you can force it to resize with resize().
I have a chunk of code:
void split(std::vector<std::string> * v,const char* s,const char* x) {
size_t len = strlen(s);
size_t slen = strlen(x); //slen = Search Length
if(len==0||slen==0)
return;
v->clear();
char* f = new char[len];
memset(f,0,len);
int * counter =new int;
(*counter)=0;
for(unsigned int i = 0; i<len; i++) {
if(isNext((s+(i*sizeof(char*))),x)) {
f[i]=1;
counter++;
}
}
if((*counter)==0) {
delete [] f;
delete counter;
v->clear();
return;
}
...
However when I am debugging it with gdb (on cygwin) or the visual studio debugger I get this error (from the cygwin console)
(gdb) step
36 if(len==0||slen==0)
(gdb) step
38 v->clear();
(gdb) step
std::vector<std::string, std::allocator<std::string> >::clear (
this=0x60003a3e0)
at /usr/lib/gcc/x86_64-pc-cygwin/4.8.2/include/c++/bits/stl_vector.h:1126
1126 { _M_erase_at_end(this->_M_impl._M_start); }
(gdb)
No matter where I compile it I get the same error! When I check the values of all the variables within gdb everything is correct (values are exactly what they should be). The vector does work because I intialize it in main(), use it and then delete it and reallocate it (all without issue). Am I missing some big thing here? Googling and debugging for hours didn't seem to bring up anything. Any help is appreciated!
There's a lot here that can be simplified, but as far as major problems there is this:
int * counter =new int;
(*counter)=0;
counter++;
The counter++ is incrementing the pointer not the value pointed to. I don't see any reason why this needs to be a pointer and should probably be avoided as it just adds complexity to this.
What does isNext do? There definitely a lot you can do to simply this and when that's done it will likely reduce problems.
What are you passing to split? If the vector is uninitialized the call to ->clear() could cause an access violation.
As above, I'm trying to create and then fill an array of structures with some starting data to then write to/read from.
I'm still writing the cache simulator as per my previous question:
Any way to get rid of the null character at the end of an istream get?
Here's how I'm making the array:
struct cacheline
{
string data;
string tag;
bool valid;
bool dirty;
};
cacheline **AllocateDynamicArray( int nRows, int nCols)
{
cacheline **dynamicArray;
dynamicArray = new cacheline*[nRows];
for( int i = 0 ; i < nRows ; i++ )
dynamicArray[i] = new cacheline [nCols];
return dynamicArray;
}
I'm calling this from main:
cacheline **cache = AllocateDynamicArray(nooflines,noofways);
It seems to create the array ok, but when I try to fill it I get memory errors, here's how I'm trying to do it:
int fillcache(cacheline **cache, int cachesize, int cachelinelength, int ways)
{
for (int j = 0; j < ways; j++)
{
for (int i = 0; i < cachesize/(cachelinelength*4); i++)
{
cache[i][ways].data = "EMPTY";
cache[i][ways].tag = "";
cache[i][ways].valid = 0;
cache[i][ways].dirty = 0;
}
}
return(1);
}
Calling it with:
fillcache(cache, cachesize, cachelinelength, noofways);
Now, this is the first time I've really tried to use dynamic arrays, so it's entirely possible I'm doing that completely wrong, let alone when trying to make it 2d, any ideas would be greatly appreciated :)
Also, is there an easier way to do write to/read from the array? At the moment (I think) I'm having to pass lots of variables to and from functions, including the array (or a pointer to the array?) each time which doesn't seem efficient?
Something else I'm unsure of, when I pass the array (pointer?) and edit the array, when I go back out of the function, will the array still be edited?
Thanks
Edit:
Just noticed a monumentally stupid error, it should ofcourse be:
cache[i][j].data = "EMPTY";
You should find your happiness. You just need the time to check it out (:
The way to happiness
How can this ever happen that this throws an exception
for(int h = 0 ; h < listOne.count() ; ++h) {
delete[] listOne[h];
}
with QList listOne ? I delete float* arrays iterating until I reach number of element in the QList ...
EDIT & SOLUTION
In fact, it fails when I am adding only one float in one item of QList. Then, it is no more a float* and you cannot delete [] it.
How can this ever happen that this throws an exception
One posibility: you added one array 2 time to the list.
One fix:
for(int h = 0 ; h < listOne.count() ; ++h) {
delete[] listOne[h];
listOne[h]=nullptr;
}
Maybe others errors (you added not-array pointers to the list).
EDIT:
In fact, it fails when I am adding only one float in one item of
QList. Then, it is no more a float* and you cannot delete [] it.
I suspected...
A very simple fix:
float *pi=new float[1];
pi[0]=3.14f;
Now add pi to the list
I had an issue where my code segfaulted on attempting to use the size() function of a list. On the advice of stackoverflow :-) I constructed a minimum case in which the segfault occurs (on the call inventory.size() below). It is:
#include <list>
class Thing {};
class Player {
private:
int xpCalcArray[99];
std::list<Thing*> inventory;
public:
Player();
int addToInv(Thing& t); // return 1 on success, 0 on failure
};
Player::Player() {
// set up XP calculation array
for (int i=1; i<100; i++) {
if (i<=10) {
xpCalcArray[i] = i*100;
}
if (i>10 && i<=50) {
xpCalcArray[i] = i*1000;
}
if (i>50 && i<=99) {
xpCalcArray[i] = i*5000;
}
}
}
int Player::addToInv(Thing& t) {
if (inventory.size() == 52) {
return 0;
} else {
inventory.push_back(&t);
}
return 1;
}
int main(int argc, char *argv[]) {
Thing t;
Player pc;
pc.addToInv(t);
return 1;
}
I notice that when I remove the setting up of the array in the Player cosntructor, it works fine, so this looks to be the problem. What am I doing wrong?
You are accessing your array out of bounds, which results in undefined behaviour. The valid index range for this array
int xpCalcArray[99];
is 0 to 98. You are accessing index 99 here:
if (i>50 && i<=99) {
xpCalcArray[i] = i*5000;
}
Your outer loop should be
for (int i=0; i<99; i++) { ... }
Note I start from 0, although it is an assumption that you actually want to access the first element.
Then your final condition can be simplified to
if (i>50) {
xpCalcArray[i] = i*5000;
}
If you intended to use a size 100 array, then you need
int xpCalcArray[100];
then loop between int i=0; i<100;.
You are accessing outside the bounds of your array. Doing so causes undefined behaviour and so there is no logical explanation for anything that occurs afterwards. The size of your array is 99 and so the last index is 98. Your for loop goes up to 99, however.
Either make your array size 100:
int xpCalcArray[100];
Or change your for condition to i < 99.
You are overwriting your array of 99 ints by attempting to modify the 2nd→100th elements (rather than 1st→99th).
In your case, this happens to overwrite some memory within the std::list<Thing*> (which exists in memory directly after the array — not always, but evidently for you today) and thus, when you try to use the list, all hell breaks loose when its internal member data is no longer what it thought it was.
You xpCalcArray is defined from 0 up to 98 (being 99 elements large).
Your loop goes from 0 up to 99, taking 100 steps.
The last loop cycle, writes xpCalcArray at location 99, which does not exist. This (indirectly) results in your segmentation fault as shown by the answer of Lightness Races in Orbit.
So, increase the size of xpCalcArray by 1:
int xpCalcArray[100];