# Stack smashing

**Stack smashing** in C++ is a form of buffer overflow. It happens when a program writes more data to the stack than its available memory allocation, causing adjacent memory locations to be overwritten.

## Example of stack smashing

Here's an example of an array containing the five numbers:

```cpp
int A[5] = {1,2,3,4,5};
A[6] = 2;
```
If we attempt to update the 6th index, the message “stack smashing detected” will be displayed on the console, and the program will end abruptly.

To grasp the concept of such behavior, refer to the illustration below.

Let's write a complete code and run it to verify the result below:

#include <iostream>
using namespace std;

int main() {
  int A[5] = {1,2,3,4,5},i;
  for(i=0;i<10;i++)
      A[i]=2;
}

# Code explanation

**Lines 6-7:** Inside the loop, it will access array elements beyond its allocated `size`, resulting in "stack smashing detected". Since the array `A` has a size of `5` in **line 5**, accessing elements beyond index `4` (as in `A[i] = 2` if `i` >= 5) leads to accessing memory locations outside the valid range of the array.

What is stack smashing in C++?

Overwriting stack memory allocation in C++ causes "stack smashing detected," ending the program abruptly.