Ошибка stack around the variable

I have a program which prompts me the error in VS2010, in debug :

Error: Stack around the variable 'x' was corrupted

This gives me the function where a stack overflow likely occurs, but I can’t visually see where the problem is.

Is there a general way to debug this error with VS2010? Would it be possible to indentify which write operation is overwritting the incorrect stack memory?
thanks

asked Oct 30, 2012 at 15:32

Is there a general way to debug this error with VS2010?

No, there isn’t. What you have done is to somehow invoke undefined behavior. The reason these behaviors are undefined is that the general case is very hard to detect/diagnose. Sometimes it is provably impossible to do so.

There are however, a somewhat smallish number of things that typically cause your problem:

• Improper handling of memory:
  • Deleting something twice,
  • Using the wrong type of deletion (free for something allocated with new, etc.),
  • Accessing something after it’s memory has been deleted.
• Returning a pointer or reference to a local.
• Reading or writing past the end of an array.

answered Oct 30, 2012 at 16:08

answered Oct 30, 2012 at 15:35

Actually what you see is quite informative, you should check in near x variable location for any activity that might cause this error.

Below is how you can reproduce such exception:

int main() {
    char buffer1[10];
    char buffer2[20];
    memset(buffer1, 0, sizeof(buffer1) + 1);
    return 0;
}

will generate (VS2010):

Run-Time Check Failure #2 — Stack around the variable ‘buffer1’ was corrupted.

obviously memset has written 1 char more than it should. VS with option GS allows to detect such buffer overflows (which you have enabled), for more on that read here: http://msdn.microsoft.com/en-us/library/Aa290051.

You can for example use debuger and step throught you code, each time watch at contents of your variable, how they change. You can also try luck with data breakpoints, you set breakpoint when some memory location changes and debugger stops at that moment,possibly showing you callstack where problem is located. But this actually might not work with GS flag.

For detecting heap overflows you can use gflags tool.

answered Oct 30, 2012 at 16:32

I was puzzled by this error for hours, I know the possible causes, and they are already mentioned in the previous answers, but I don’t allocate memory, don’t access array elements, don’t return pointers to local variables…

Then finally found the source of the problem:

*x++;

The intent was to increment the pointed value. But due to the precedence ++ comes first, moving the x pointer forward then * does nothing, then writing to *x will be corrupt the stack canary if the parameter comes from the stack, making VS complain.

Changing it to (*x)++ solves the problem.

Hope this helps.

answered Jan 7, 2014 at 13:31

Here is what I do in this situation:

Set a breakpoint at a location where you can see the (correct) value of the variable in question, but before the error happens. You will need the memory address of the variable whose stack is being corrupted. Sometimes I have to add a line of code in order for the debugger to give me the address easily (int *x = &y)

At this point you can set a memory breakpoint (Debug->New Breakpoint->New Data Breakpoint)

Hit Play and the debugger should stop when the memory is written to. Look up the stack (mine usually breaks in some assembly code) to see whats being called.

answered Oct 30, 2012 at 16:04

I usually follow the variable before the complaining variable which usually helps me get the problem. But this can sometime be very complex with no clue as you have seen it. You could enable Debug menu >> Exceptions and tick the ‘Win32 exceptions» to catch all exceptions. This will still not catch this exceptions but it could catch something else which could indirectly point to the problem.

In my case it was caused by library I was using. It turnout the header file I was including in my project didn’t quite match the actual header file in that library (by one line).

There is a different error which is also related:

0xC015000F: The activation context being deactivated is not the most
recently activated one.

When I got tired of getting the mysterious stack corrupted message on my computer with no debugging information, I tried my project on another computer and it was giving me the above message instead. With the new exception I was able to work my way out.

answered Jun 16, 2014 at 15:48

answered Oct 9, 2015 at 5:50

One relatively common source of «Stack around the variable ‘x’ was corrupted» problem is wrong casting. It is sometimes hard to spot. Here is an example of a function where such problem occurs and the fix. In the function assignValue I want to assign some value to a variable. The variable is located at the memory address passed as argument to the function:

using namespace std;
            
template<typename T>
void assignValue(uint64_t address, T value)
{
    int8_t* begin_object = reinterpret_cast<int8_t*>(std::addressof(value));
    // wrongly casted to (int*), produces the error (sizeof(int) == 4)
    //std::copy(begin_object, begin_object + sizeof(T), (int*)address);  
    // correct cast to (int8_t*), assignment byte by byte, (sizeof(int8_t) == 1)
    std::copy(begin_object, begin_object + sizeof(T), (int8_t*)address); 
}
        
int main()
{
    int x = 1;
    int x2 = 22;
    assignValue<int>((uint64_t)&x, x2);
    assert(x == x2);
}

answered Feb 1, 2021 at 9:36

void GameBoard::enterShips()
{
    char location[1];
    int ships = 0;
    int count = 1;

    while(ships < NUM_SHIPS)
    {
        cout << "Enter a location for Ship " << count << ": ";
        cin >> location;
        cout << endl;

        Grid[location[0]][location[1]] = SHIP;
        ships++;
        count++;
    }
}

Im writing a battleship game. I have the board layouts working and the computers randomly generated ships. Now I am working on this method to prompt the user to enter coordinates for the ships When I run the program, it allows me to enter 5 ships. When I enter the 6th ship, it gives me this error.

Stack around the variable location was corrupted.

Ive looked for answers online and have not found anything exclusive.

Any help would be appreciated.

answered Feb 27, 2011 at 21:00

cin >> location;

location is an array of one char. This can’t succeed because when you read from a stream into a char array, a null terminator has to be added (which takes one character). You will inevitably overrun the bounds of the array.

You can use a std::string, which will help you avoid any buffer overrun issues:

std::string location;
if (!(std::cin >> location)) {
    // handle input error
}

Note also that you probably need to convert the string representations of the numbers into numeric values. You can easily do this by reading from the stream into two int objects instead:

int x_location, y_location;
if (!(std::cin >> x_location >> y_location)) { 
    // Handle input error
}

if (x_location >= X_DIMENSION || x_location < 0 ||
    y_location >= Y_DIMENSION || y_location < 0) {
    // Handle out-of-range error 
}

// use x_location and y_location

answered Feb 27, 2011 at 21:04

You made the location variable only able to hold a single character. You access it expecting it to hold at least 2 characters. If you’re using cin and expecting to read exactly two characters, a better method would be:

char locationX, locationY;
// ...
std::cin >> locationX >> locationY;
// ...
Grid[locationX][locationY] = SHIP;

answered Feb 27, 2011 at 21:01

I wrote a program to calculate the average of 10 grades a user inputs. The program works and gives me the average, but at the end when it’s supposed to close I get this error: «Run-Time Check Failure #2 — Stack around the variable ‘grade’ was corrupted.»

I’ve posted the code below. Also, I have to make it calculate median and mode as well. I think I can figure out median, but can anyone help me to get started on mode?

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86

#include "stdafx.h"
#include <iostream>
using namespace std;
int main()
 {
	//Create an array with 10 elements
	float grade[10];
	int count;
	float tscore = 0;
	//Set precision of Average, will be displayed with a decimal
	double average;
	for (count = 1; count <= 10; count++)
	 {
		cout << "Enter Grade " << count << ": ";
		 {
		cin >> grade[count];
	 }}

	for(count = 1; count <= 10; count++)
		tscore = tscore + grade[count];
	average = tscore/10;
	
	//Assign letter grade corresponding to number grade
	if((average >= 0) && (average < 60))
	{
		cout<<"The average is an F."<<endl;
	}
	else if((average >= 60) && (average < 63))
	{
		cout<<"The average is a D-."<<endl;
	}
	else if((average >= 63) && (average < 67))
	{
		cout<<"The average is a D."<<endl;
	}
	else if((average >= 67) && (average < 70))
	{
		cout<<"The average is a D+."<<endl;
	}
	else if((average >= 70) && (average < 73))
	{
		cout<<"The average is a C-."<<endl;
	}
	else if((average >= 73) && (average < 77))
	{
		cout<<"The average is a C."<<endl;
	}
	else if((average >= 77) && (average < 80))
	{
		cout<<"The average is a C+."<<endl;
	}
	else if((average >= 80) && (average < 83))
	{
		cout<<"The average is a B-."<<endl;
	}
	else if((average >= 83) && (average < 87))
	{
		cout<<"The average is a B."<<endl;
	}
	else if((average >= 87) && (average < 90))
	{
		cout<<"The average is a B+."<<endl;
	}
	else if((average >= 90) && (average < 93))
	{
		cout<<"The average is an A-."<<endl;
	}
	else if((average >= 93) && (average < 97))
	{
		cout<<"The average is an A."<<endl;
	}
	else if((average >= 97) && (average <= 100))
	{
		cout<<"The average is an A+."<<endl;
	}
	else
	{
		cout<<"The average is not between 0 and 100, please reenter the grades with values between 0 and 100."<<endl;
	}

	//Output
	cout << "The average of the ten grades you entered is: " << average << endl;

	system("PAUSE"); 
	return 0;
}

Thanks working now. Just one minor problem, it now says Enter Grade 0 for the first grade. Is there any simple way I can change that? If not, it’s fine how it is.

Also, how could I get the mode? Not asking for any code, just point me in the right direction. I know I’m going to have to use count, but not sure how to implement it.

Thanks

You could change it to cout << "Enter Grade " << count+1 << ": ";

As for the mode, there’s an STL algorithm called «count» that will return the amount of times something occurs in a range. Might be worth taking a look at http://www.cplusplus.com/reference/algorithm/count/

Still trying to figure that out, almost have median done though.

I need to move the median = … and the cout below to within the loop, but not sure where. Haven’t gotten a right answer anywhere I put it while testing.

Uses bubble sorting to order and then I take the middle two numbers (since its 10, even) and add them up and divide by 2.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20

	//Calculate Median
	bool done;
	double temp;
	double median;
	while (done == false)
	{
	done = true;  //Done is a boolean value that is set to true by default, if it's left unchanged then we are done
	for (int i = 0; i < 9; i++)
		{
			if (grade[i] > grade[i+1])  //If the next value in the array is smaller than the current value, then we need to swap them.
				{
					temp = grade[i+1];  //Store the second value into a temporary variable first so we don't lose it
					grade[i+1] = grade[i];  //Then set the second value to the current value.
					grade[i] = temp;  //Afterwards place the stored temporary value into the current value
					done = false;   //Since we had to change a value, we are obviously not done, so when the loop completes, it will do another iteration.
	}
	}
	}
	median = (grade[5] + grade[6])/2;
	cout << "The median of the ten grades you entered is: " << median << endl;

I guess that would be wrong too. Right now I’m getting a Runtime error and it’s outputting a median, but the median is wrong. It’s taking the median of grade[5] and grade[6] without ordering them.

Full code: (Median begins on line 89)

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115

// GradeMean.cpp : Defines the entry point for the console application.

#include "stdafx.h"
#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
int main()
 {
	float grade[10]; //Create an array with 10 elements
	int count;
	float tscore = 0;
	double average;
	
	//Input Grades
	for (count = 0; count <= 9; count++)
	 {
		cout << "Enter Grade " << count+1 << ": ";
		 {
		cin >> grade[count];
	 }}

	//Calculate Average
	for(count = 0; count <= 9; count++)
		tscore = tscore + grade[count];
	average = tscore/10;
	
	//Assign letter grade corresponding to number grade
	if((average >= 0) && (average < 60)) 
	{
		cout<<"The average is an F."<<endl;
	}
	else if((average >= 60) && (average < 63))
	{
		cout<<"The average is a D-."<<endl;
	}
	else if((average >= 63) && (average < 67))
	{
		cout<<"The average is a D."<<endl;
	}
	else if((average >= 67) && (average < 70))
	{
		cout<<"The average is a D+."<<endl;
	}
	else if((average >= 70) && (average < 73))
	{
		cout<<"The average is a C-."<<endl;
	}
	else if((average >= 73) && (average < 77))
	{
		cout<<"The average is a C."<<endl;
	}
	else if((average >= 77) && (average < 80))
	{
		cout<<"The average is a C+."<<endl;
	}
	else if((average >= 80) && (average < 83))
	{
		cout<<"The average is a B-."<<endl;
	}
	else if((average >= 83) && (average < 87))
	{
		cout<<"The average is a B."<<endl;
	}
	else if((average >= 87) && (average < 90))
	{
		cout<<"The average is a B+."<<endl;
	}
	else if((average >= 90) && (average < 93))
	{
		cout<<"The average is an A-."<<endl;
	}
	else if((average >= 93) && (average < 97))
	{
		cout<<"The average is an A."<<endl;
	}
	else if((average >= 97) && (average <= 100))
	{
		cout<<"The average is an A+."<<endl;
	}
	else
	{
		cout<<"The average is not between 0 and 100, please reenter the grades with values between 0 and 100."<<endl;
	}

	//Output
	cout << "The average of the ten grades you entered is: " << average << endl;

	//Calculate Median
	bool done;
	double temp;
	double median;
	while (done == false)
	{
	done = true;  //Done is a boolean value that is set to true by default, if it's left unchanged then we are done
	for (int i = 0; i < 9; i++)
		{
			if (grade[i] > grade[i+1])  //If the next value in the array is smaller than the current value, then we need to swap them.
				{
					temp = grade[i+1];  //Store the second value into a temporary variable first so we don't lose it
					grade[i+1] = grade[i];  //Then set the second value to the current value.
					grade[i] = temp;  //Afterwards place the stored temporary value into the current value
					done = false;   //Since we had to change a value, we are obviously not done, so when the loop completes, it will do another iteration.
	}
	}
	}
	median = (grade[5] + grade[6])/2;
	cout << "The median of the ten grades you entered is: " << median << endl;

	//Calculate Mode
	

	system("PAUSE"); 
	return 0;
}

I know, I changed it to 5 and 6 from 4 and 5. It would be 4 and 5 if I didn’t add 1 to count, so it should be 5 and 6, so I don’t think that’s the problem. Unless I’m missing something, which is definitely possible…

thanks

You’re got it backwards, cmorris1441.

In regular numbers:
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 |

Array indices:
| 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 |

Look vertically to see how the numbers correspond, If you want the 4th and 5th elements of the regular numbers, you’ll want to use indices 3 and 4.
so median = (grade[3] + grade[4])/2

You’re right, just changed it and entered 91-100 randomly (once each) and got a median of 94 though…

Also, I’m getting an error:
Run-Time Check Failure #3 — The variable ‘done’ is being used without being initialized.

Program still runs when I click continue.

The variable ‘done’ is being used without being initialized.

Believe it or not, but that’s directly related to the fact that you’re not initializing ‘done’.

It is now, I have 2 programs and was looking at the wrong one. Here’s what I now have, still not getting the median correct.

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115

// GradeMean.cpp : Defines the entry point for the console application.

#include "stdafx.h"
#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
int main()
 {
	float grade[10]; //Create an array with 10 elements
	int count;
	float tscore = 0;
	double average;
	
	//Input Grades
	for (count = 0; count <= 9; count++)
	 {
		cout << "Enter Grade " << count+1 << ": ";
		 {
		cin >> grade[count];
	 }}

	//Calculate Mean
	for(count = 0; count <= 9; count++)
		tscore = tscore + grade[count];
	average = tscore/10;
	
	//Assign letter grade corresponding to number grade
	if((average >= 0) && (average < 60)) 
	{
		cout<<"The average is an F."<<endl;
	}
	else if((average >= 60) && (average < 63))
	{
		cout<<"The average is a D-."<<endl;
	}
	else if((average >= 63) && (average < 67))
	{
		cout<<"The average is a D."<<endl;
	}
	else if((average >= 67) && (average < 70))
	{
		cout<<"The average is a D+."<<endl;
	}
	else if((average >= 70) && (average < 73))
	{
		cout<<"The average is a C-."<<endl;
	}
	else if((average >= 73) && (average < 77))
	{
		cout<<"The average is a C."<<endl;
	}
	else if((average >= 77) && (average < 80))
	{
		cout<<"The average is a C+."<<endl;
	}
	else if((average >= 80) && (average < 83))
	{
		cout<<"The average is a B-."<<endl;
	}
	else if((average >= 83) && (average < 87))
	{
		cout<<"The average is a B."<<endl;
	}
	else if((average >= 87) && (average < 90))
	{
		cout<<"The average is a B+."<<endl;
	}
	else if((average >= 90) && (average < 93))
	{
		cout<<"The average is an A-."<<endl;
	}
	else if((average >= 93) && (average < 97))
	{
		cout<<"The average is an A."<<endl;
	}
	else if((average >= 97) && (average <= 100))
	{
		cout<<"The average is an A+."<<endl;
	}
	else
	{
		cout<<"The average is not between 0 and 100, please reenter the grades with values between 0 and 100."<<endl;
	}

	//Output
	cout << "The average of the ten grades you entered is: " << average << endl;

	//Calculate Median
	bool done = false;
	double temp;
	double median;
	while (done == false)
	{
	done = true;  //Done is a boolean value that is set to true by default, if it's left unchanged then we are done
	for (int i = 0; i < 9; i++)
		{
			if (grade[i] > grade[i+1])  //If the next value in the array is smaller than the current value, then we need to swap them.
				{
					temp = grade[i+1];  //Store the second value into a temporary variable first so we don't lose it
					grade[i+1] = grade[i];  //Then set the second value to the current value.
					grade[i] = temp;  //Afterwards place the stored temporary value into the current value
					done = false;   //Since we had to change a value, we are obviously not done, so when the loop completes, it will do another iteration.
	}
	}
	}
	median = (grade[3] + grade[4])/2;
	cout << "The median of the ten grades you entered is: " << median << endl;

	//Calculate Mode
	

	system("PAUSE"); 
	return 0;
}

Wasn’t thinking when I corrected it earlier. Thanks. Median and Mean both work now.

Thanks Athar and Thumper for all the help.