C++ crash after printing 2 dimensional array
-2
After printing a 2-dimensional array, my program crashes and I don't know why. The program crashes before "test2" is printed:
//initialising
int** matrix = new int*[x * y];
for (int i = 0; i < x; i++){
matrix[i] = new int[y];
}
//filling with 0
for (int row = 0; row < x; row++){
for (int cols = 0; cols < y; cols++){
matrix [row][cols] = 0;
}
}
//printing
for(int i = 0; i < x; ++i) {
for(int j = 0; j < y; ++j){
std::cout << (matrix[i][j]) << ", ";
}
std::cout << std::endl;
}
std::cout << "test2" << std::endl;
c++ matrix multidimensional-array crash
edited Nov 18 '18 at 23:54
Shrikanth N
510211
asked Nov 18 '18 at 16:00
B.abyfaceB.abyface
43
|
show 3 more comments
-2
After printing a 2-dimensional array, my program crashes and I don't know why. The program crashes before "test2" is printed:
//initialising
int** matrix = new int*[x * y];
for (int i = 0; i < x; i++){
matrix[i] = new int[y];
}
//filling with 0
for (int row = 0; row < x; row++){
for (int cols = 0; cols < y; cols++){
matrix [row][cols] = 0;
}
}
//printing
for(int i = 0; i < x; ++i) {
for(int j = 0; j < y; ++j){
std::cout << (matrix[i][j]) << ", ";
}
std::cout << std::endl;
}
std::cout << "test2" << std::endl;
c++ matrix multidimensional-array crash
edited Nov 18 '18 at 23:54
Shrikanth N
510211
asked Nov 18 '18 at 16:00
B.abyfaceB.abyface
43
2
What's time? And size? Why are you allocatingint** matrix = new int*[x*y];but then only allocatexsubpointers?
– Matthieu Brucher
Nov 18 '18 at 16:04
1
Possible duplicate of How do I declare a 2d array in C++ using new?
– Matthieu Brucher
Nov 18 '18 at 16:06
FWIW, When I build and run the code you have posted (supplying my own values for x and y), it runs without issue. I also ran the static analyzer on it and no issues were found. I ran it using Address Sanitizer and it did not cause any issues. I ran it using Guard Malloc, Malloc Scribble, and Malloc Guard Edges together and no issues were found. It would seem the problem isn't with the above cod snippet, so perhaps some more context would reveal the problem?
– user1118321
Nov 18 '18 at 16:30
@user1118321 I too ran the address sanitizer and Valgrind memtool. Both reported memory leaks.
– Bo R
Nov 18 '18 at 17:13
1
Your initilizing code is allocating too much. Should beint **matrix = new int *[x];(instead of x*y). And hopefully you are deallocating later on.for (int i = 0; i < x; i++) delete matrix[i]; delete matrix;
– Bo R
Nov 18 '18 at 17:20
|
show 3 more comments
-2
-2
-2
After printing a 2-dimensional array, my program crashes and I don't know why. The program crashes before "test2" is printed:
//initialising
int** matrix = new int*[x * y];
for (int i = 0; i < x; i++){
matrix[i] = new int[y];
}
//filling with 0
for (int row = 0; row < x; row++){
for (int cols = 0; cols < y; cols++){
matrix [row][cols] = 0;
}
}
//printing
for(int i = 0; i < x; ++i) {
for(int j = 0; j < y; ++j){
std::cout << (matrix[i][j]) << ", ";
}
std::cout << std::endl;
}
std::cout << "test2" << std::endl;
c++ matrix multidimensional-array crash
edited Nov 18 '18 at 23:54
Shrikanth N
510211
asked Nov 18 '18 at 16:00
B.abyfaceB.abyface
43
After printing a 2-dimensional array, my program crashes and I don't know why. The program crashes before "test2" is printed:
//initialising
int** matrix = new int*[x * y];
for (int i = 0; i < x; i++){
matrix[i] = new int[y];
}
//filling with 0
for (int row = 0; row < x; row++){
for (int cols = 0; cols < y; cols++){
matrix [row][cols] = 0;
}
}
//printing
for(int i = 0; i < x; ++i) {
for(int j = 0; j < y; ++j){
std::cout << (matrix[i][j]) << ", ";
}
std::cout << std::endl;
}
std::cout << "test2" << std::endl;
c++ matrix multidimensional-array crash
c++ matrix multidimensional-array crash
edited Nov 18 '18 at 23:54
Shrikanth N
510211
asked Nov 18 '18 at 16:00
B.abyfaceB.abyface
43
edited Nov 18 '18 at 23:54
Shrikanth N
510211
asked Nov 18 '18 at 16:00
B.abyfaceB.abyface
43
edited Nov 18 '18 at 23:54
Shrikanth N
510211
edited Nov 18 '18 at 23:54
Shrikanth N
510211
edited Nov 18 '18 at 23:54
Shrikanth N
510211
510211
asked Nov 18 '18 at 16:00
B.abyfaceB.abyface
43
asked Nov 18 '18 at 16:00
B.abyfaceB.abyface
43
asked Nov 18 '18 at 16:00
B.abyfaceB.abyface
43
43
2
What's time? And size? Why are you allocatingint** matrix = new int*[x*y];but then only allocatexsubpointers?
– Matthieu Brucher
Nov 18 '18 at 16:04
1
Possible duplicate of How do I declare a 2d array in C++ using new?
– Matthieu Brucher
Nov 18 '18 at 16:06
FWIW, When I build and run the code you have posted (supplying my own values for x and y), it runs without issue. I also ran the static analyzer on it and no issues were found. I ran it using Address Sanitizer and it did not cause any issues. I ran it using Guard Malloc, Malloc Scribble, and Malloc Guard Edges together and no issues were found. It would seem the problem isn't with the above cod snippet, so perhaps some more context would reveal the problem?
– user1118321
Nov 18 '18 at 16:30
@user1118321 I too ran the address sanitizer and Valgrind memtool. Both reported memory leaks.
– Bo R
Nov 18 '18 at 17:13
1
Your initilizing code is allocating too much. Should beint **matrix = new int *[x];(instead of x*y). And hopefully you are deallocating later on.for (int i = 0; i < x; i++) delete matrix[i]; delete matrix;
– Bo R
Nov 18 '18 at 17:20
|
show 3 more comments
2
What's time? And size? Why are you allocatingint** matrix = new int*[x*y];but then only allocatexsubpointers?
– Matthieu Brucher
Nov 18 '18 at 16:04
1
Possible duplicate of How do I declare a 2d array in C++ using new?
– Matthieu Brucher
Nov 18 '18 at 16:06
FWIW, When I build and run the code you have posted (supplying my own values for x and y), it runs without issue. I also ran the static analyzer on it and no issues were found. I ran it using Address Sanitizer and it did not cause any issues. I ran it using Guard Malloc, Malloc Scribble, and Malloc Guard Edges together and no issues were found. It would seem the problem isn't with the above cod snippet, so perhaps some more context would reveal the problem?
– user1118321
Nov 18 '18 at 16:30
@user1118321 I too ran the address sanitizer and Valgrind memtool. Both reported memory leaks.
– Bo R
Nov 18 '18 at 17:13
1
Your initilizing code is allocating too much. Should beint **matrix = new int *[x];(instead of x*y). And hopefully you are deallocating later on.for (int i = 0; i < x; i++) delete matrix[i]; delete matrix;
– Bo R
Nov 18 '18 at 17:20
2
2
What's time? And size? Why are you allocating
int** matrix = new int*[x*y]; but then only allocate x subpointers?– Matthieu Brucher
Nov 18 '18 at 16:04
What's time? And size? Why are you allocating
int** matrix = new int*[x*y]; but then only allocate x subpointers?– Matthieu Brucher
Nov 18 '18 at 16:04
1
1
Possible duplicate of How do I declare a 2d array in C++ using new?
– Matthieu Brucher
Nov 18 '18 at 16:06
Possible duplicate of How do I declare a 2d array in C++ using new?
– Matthieu Brucher
Nov 18 '18 at 16:06
FWIW, When I build and run the code you have posted (supplying my own values for x and y), it runs without issue. I also ran the static analyzer on it and no issues were found. I ran it using Address Sanitizer and it did not cause any issues. I ran it using Guard Malloc, Malloc Scribble, and Malloc Guard Edges together and no issues were found. It would seem the problem isn't with the above cod snippet, so perhaps some more context would reveal the problem?
– user1118321
Nov 18 '18 at 16:30
FWIW, When I build and run the code you have posted (supplying my own values for x and y), it runs without issue. I also ran the static analyzer on it and no issues were found. I ran it using Address Sanitizer and it did not cause any issues. I ran it using Guard Malloc, Malloc Scribble, and Malloc Guard Edges together and no issues were found. It would seem the problem isn't with the above cod snippet, so perhaps some more context would reveal the problem?
– user1118321
Nov 18 '18 at 16:30
@user1118321 I too ran the address sanitizer and Valgrind memtool. Both reported memory leaks.
– Bo R
Nov 18 '18 at 17:13
@user1118321 I too ran the address sanitizer and Valgrind memtool. Both reported memory leaks.
– Bo R
Nov 18 '18 at 17:13
1
1
Your initilizing code is allocating too much. Should be
int **matrix = new int *[x]; (instead of x*y). And hopefully you are deallocating later on. for (int i = 0; i < x; i++) delete matrix[i]; delete matrix;– Bo R
Nov 18 '18 at 17:20
Your initilizing code is allocating too much. Should be
int **matrix = new int *[x]; (instead of x*y). And hopefully you are deallocating later on. for (int i = 0; i < x; i++) delete matrix[i]; delete matrix;– Bo R
Nov 18 '18 at 17:20
|
show 3 more comments
1 Answer
1
active
oldest
votes
1
#include<iostream>
void func(int x, int y)
{
// initialising
int **matrix = new int *[x];
for (int i = 0; i < x; i++)
{
matrix[i] = new int[y];
}
// filling with 0
for (int row = 0; row < x; row++)
{
for (int cols = 0; cols < y; cols++)
{
matrix[row][cols] = 0;
}
}
// printing
for (int i = 0; i < (x); ++i)
{
for (int j = 0; j < (y); ++j)
{
std::cout << (matrix[i][j]) << ", ";
}
std::cout << std::endl;
}
std::cout << "test2" << std::endl;
for(int i = 0; i < x; i++)
deletematrix[i]; // clean up each y
deletematrix; // clean up x
}
int main()
{
func(5, 5);
}
your x array only needs to be x long. each of your x pointers point to an array that is y long. when calling new you must call delete on each pointer allocated by new to prevent memory leaks. Here is verification of the code https://ideone.com/UL2IJn
answered Nov 18 '18 at 17:45
johnathanjohnathan
2,158819
While this is all true, it's not obvious to me that any of this was the cause of the crash. While the array had space for a bunch of extra pointers that weren't allocated, it also didn't ever read or write to them. So what caused the crash?
– user1118321
Nov 18 '18 at 17:52
@user1118321 i do not have access to the OP's machine. Programatically there is nothing that, given the narrow scope of their snippet, would indicate an exception would be thrown other than potentially std::bad_alloc, which is why i also supplied a reasonable matrix size of 5 by 5.
– johnathan
Nov 18 '18 at 17:59
Thanks @johnathan. Just wanted to make sure I wasn't missing something in what you wrote. Things like this intrigue me. :-)
– user1118321
Nov 18 '18 at 18:00
add a comment |
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1
#include<iostream>
void func(int x, int y)
{
// initialising
int **matrix = new int *[x];
for (int i = 0; i < x; i++)
{
matrix[i] = new int[y];
}
// filling with 0
for (int row = 0; row < x; row++)
{
for (int cols = 0; cols < y; cols++)
{
matrix[row][cols] = 0;
}
}
// printing
for (int i = 0; i < (x); ++i)
{
for (int j = 0; j < (y); ++j)
{
std::cout << (matrix[i][j]) << ", ";
}
std::cout << std::endl;
}
std::cout << "test2" << std::endl;
for(int i = 0; i < x; i++)
deletematrix[i]; // clean up each y
deletematrix; // clean up x
}
int main()
{
func(5, 5);
}
your x array only needs to be x long. each of your x pointers point to an array that is y long. when calling new you must call delete on each pointer allocated by new to prevent memory leaks. Here is verification of the code https://ideone.com/UL2IJn
answered Nov 18 '18 at 17:45
johnathanjohnathan
2,158819
While this is all true, it's not obvious to me that any of this was the cause of the crash. While the array had space for a bunch of extra pointers that weren't allocated, it also didn't ever read or write to them. So what caused the crash?
– user1118321
Nov 18 '18 at 17:52
@user1118321 i do not have access to the OP's machine. Programatically there is nothing that, given the narrow scope of their snippet, would indicate an exception would be thrown other than potentially std::bad_alloc, which is why i also supplied a reasonable matrix size of 5 by 5.
– johnathan
Nov 18 '18 at 17:59
Thanks @johnathan. Just wanted to make sure I wasn't missing something in what you wrote. Things like this intrigue me. :-)
– user1118321
Nov 18 '18 at 18:00
add a comment |
1
#include<iostream>
void func(int x, int y)
{
// initialising
int **matrix = new int *[x];
for (int i = 0; i < x; i++)
{
matrix[i] = new int[y];
}
// filling with 0
for (int row = 0; row < x; row++)
{
for (int cols = 0; cols < y; cols++)
{
matrix[row][cols] = 0;
}
}
// printing
for (int i = 0; i < (x); ++i)
{
for (int j = 0; j < (y); ++j)
{
std::cout << (matrix[i][j]) << ", ";
}
std::cout << std::endl;
}
std::cout << "test2" << std::endl;
for(int i = 0; i < x; i++)
deletematrix[i]; // clean up each y
deletematrix; // clean up x
}
int main()
{
func(5, 5);
}
your x array only needs to be x long. each of your x pointers point to an array that is y long. when calling new you must call delete on each pointer allocated by new to prevent memory leaks. Here is verification of the code https://ideone.com/UL2IJn
answered Nov 18 '18 at 17:45
johnathanjohnathan
2,158819
While this is all true, it's not obvious to me that any of this was the cause of the crash. While the array had space for a bunch of extra pointers that weren't allocated, it also didn't ever read or write to them. So what caused the crash?
– user1118321
Nov 18 '18 at 17:52
@user1118321 i do not have access to the OP's machine. Programatically there is nothing that, given the narrow scope of their snippet, would indicate an exception would be thrown other than potentially std::bad_alloc, which is why i also supplied a reasonable matrix size of 5 by 5.
– johnathan
Nov 18 '18 at 17:59
Thanks @johnathan. Just wanted to make sure I wasn't missing something in what you wrote. Things like this intrigue me. :-)
– user1118321
Nov 18 '18 at 18:00
add a comment |
1
1
1
#include<iostream>
void func(int x, int y)
{
// initialising
int **matrix = new int *[x];
for (int i = 0; i < x; i++)
{
matrix[i] = new int[y];
}
// filling with 0
for (int row = 0; row < x; row++)
{
for (int cols = 0; cols < y; cols++)
{
matrix[row][cols] = 0;
}
}
// printing
for (int i = 0; i < (x); ++i)
{
for (int j = 0; j < (y); ++j)
{
std::cout << (matrix[i][j]) << ", ";
}
std::cout << std::endl;
}
std::cout << "test2" << std::endl;
for(int i = 0; i < x; i++)
deletematrix[i]; // clean up each y
deletematrix; // clean up x
}
int main()
{
func(5, 5);
}
your x array only needs to be x long. each of your x pointers point to an array that is y long. when calling new you must call delete on each pointer allocated by new to prevent memory leaks. Here is verification of the code https://ideone.com/UL2IJn
answered Nov 18 '18 at 17:45
johnathanjohnathan
2,158819
#include<iostream>
void func(int x, int y)
{
// initialising
int **matrix = new int *[x];
for (int i = 0; i < x; i++)
{
matrix[i] = new int[y];
}
// filling with 0
for (int row = 0; row < x; row++)
{
for (int cols = 0; cols < y; cols++)
{
matrix[row][cols] = 0;
}
}
// printing
for (int i = 0; i < (x); ++i)
{
for (int j = 0; j < (y); ++j)
{
std::cout << (matrix[i][j]) << ", ";
}
std::cout << std::endl;
}
std::cout << "test2" << std::endl;
for(int i = 0; i < x; i++)
deletematrix[i]; // clean up each y
deletematrix; // clean up x
}
int main()
{
func(5, 5);
}
your x array only needs to be x long. each of your x pointers point to an array that is y long. when calling new you must call delete on each pointer allocated by new to prevent memory leaks. Here is verification of the code https://ideone.com/UL2IJn
answered Nov 18 '18 at 17:45
johnathanjohnathan
2,158819
edited Nov 18 '18 at 19:52
answered Nov 18 '18 at 17:45
johnathanjohnathan
2,158819
answered Nov 18 '18 at 17:45
johnathanjohnathan
2,158819
answered Nov 18 '18 at 17:45
johnathanjohnathan
2,158819
2,158819
While this is all true, it's not obvious to me that any of this was the cause of the crash. While the array had space for a bunch of extra pointers that weren't allocated, it also didn't ever read or write to them. So what caused the crash?
– user1118321
Nov 18 '18 at 17:52
@user1118321 i do not have access to the OP's machine. Programatically there is nothing that, given the narrow scope of their snippet, would indicate an exception would be thrown other than potentially std::bad_alloc, which is why i also supplied a reasonable matrix size of 5 by 5.
– johnathan
Nov 18 '18 at 17:59
Thanks @johnathan. Just wanted to make sure I wasn't missing something in what you wrote. Things like this intrigue me. :-)
– user1118321
Nov 18 '18 at 18:00
add a comment |
While this is all true, it's not obvious to me that any of this was the cause of the crash. While the array had space for a bunch of extra pointers that weren't allocated, it also didn't ever read or write to them. So what caused the crash?
– user1118321
Nov 18 '18 at 17:52
@user1118321 i do not have access to the OP's machine. Programatically there is nothing that, given the narrow scope of their snippet, would indicate an exception would be thrown other than potentially std::bad_alloc, which is why i also supplied a reasonable matrix size of 5 by 5.
– johnathan
Nov 18 '18 at 17:59
Thanks @johnathan. Just wanted to make sure I wasn't missing something in what you wrote. Things like this intrigue me. :-)
– user1118321
Nov 18 '18 at 18:00
While this is all true, it's not obvious to me that any of this was the cause of the crash. While the array had space for a bunch of extra pointers that weren't allocated, it also didn't ever read or write to them. So what caused the crash?
– user1118321
Nov 18 '18 at 17:52
While this is all true, it's not obvious to me that any of this was the cause of the crash. While the array had space for a bunch of extra pointers that weren't allocated, it also didn't ever read or write to them. So what caused the crash?
– user1118321
Nov 18 '18 at 17:52
@user1118321 i do not have access to the OP's machine. Programatically there is nothing that, given the narrow scope of their snippet, would indicate an exception would be thrown other than potentially std::bad_alloc, which is why i also supplied a reasonable matrix size of 5 by 5.
– johnathan
Nov 18 '18 at 17:59
@user1118321 i do not have access to the OP's machine. Programatically there is nothing that, given the narrow scope of their snippet, would indicate an exception would be thrown other than potentially std::bad_alloc, which is why i also supplied a reasonable matrix size of 5 by 5.
– johnathan
Nov 18 '18 at 17:59
Thanks @johnathan. Just wanted to make sure I wasn't missing something in what you wrote. Things like this intrigue me. :-)
– user1118321
Nov 18 '18 at 18:00
Thanks @johnathan. Just wanted to make sure I wasn't missing something in what you wrote. Things like this intrigue me. :-)
– user1118321
Nov 18 '18 at 18:00
add a comment |
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2
What's time? And size? Why are you allocating
int** matrix = new int*[x*y];but then only allocatexsubpointers?– Matthieu Brucher
Nov 18 '18 at 16:04
1
Possible duplicate of How do I declare a 2d array in C++ using new?
– Matthieu Brucher
Nov 18 '18 at 16:06
FWIW, When I build and run the code you have posted (supplying my own values for x and y), it runs without issue. I also ran the static analyzer on it and no issues were found. I ran it using Address Sanitizer and it did not cause any issues. I ran it using Guard Malloc, Malloc Scribble, and Malloc Guard Edges together and no issues were found. It would seem the problem isn't with the above cod snippet, so perhaps some more context would reveal the problem?
– user1118321
Nov 18 '18 at 16:30
@user1118321 I too ran the address sanitizer and Valgrind memtool. Both reported memory leaks.
– Bo R
Nov 18 '18 at 17:13
1
Your initilizing code is allocating too much. Should be
int **matrix = new int *[x];(instead of x*y). And hopefully you are deallocating later on.for (int i = 0; i < x; i++) delete matrix[i]; delete matrix;– Bo R
Nov 18 '18 at 17:20