How can I solve this run time error in C ? - "Stack around variable was corrupted"-CodePudding

I try to obtain the minimum of two integers, real numbers, strings, and integer arrays by implementing functions that obtain similar treatment results as function overloading.

So I write code like this

#include <iostream>  
#include <cstring>    
using namespace std;  

int GetMin(int a, int b);
double GetMin(double a, double b);
char* GetMin(char* a, char* b);
int GetMin(int* arr, int size);


int main()
{
  int num1, num2;
  double num3, num4;
  char s1[30], s2[30];
  int arr[10];

  cout << "Enter two integers : ";
  cin >> num1 >> num2;
  cout << "The minimum value is " << GetMin(num1, num2) <<"\n";

  cout << "Enter two real numbers : ";
  cin >> num3 >> num4;
  cout << "The minimum value is " << GetMin(num3, num4) <<"\n";

  cout << "Enter two strings : ";
  cin >> s1 >> s2;
  cout << "The minimum value is " << GetMin(s1,s2) <<"\n";

  cout << "Elements of an Array : ";
  cin >> arr[10];
  cout << "The minimum value is " << GetMin(arr[10], 10);


}


int GetMin(int a, int b)
{
  if (a > b) return b;
  else return a;


}


double GetMin(double a, double b)
{
  if (a > b) return b;
  else return a;

}


  char* GetMin(char* a, char* b)
{
    if (strcmp(a, b) < 0) return a; 

}


  int GetMin(int* arr, int size)
{
    int min = arr[0];
    for (int i = 1; i<size; i  )
        if (arr[i] < min)
            min = arr[i];
    return min;

}

Here's the desired result.

Enter two integers : 10 20 
The minimum value is 10
Enter two real numbers : 56.84 120.26
The minimum value is 56.84
Enter two strings : orange apple
The minimum value is apple
Elements of an Array : 41 67 34 25 0 54 98 21 58 62
The minimum value is 0

I got this error message.

Run-Time Check Failure #2 - Stack around the variable 'arr' was corrupted.

CodePudding user response：

You have undefined behaviour, caused by this attempt to read into an index beyond the array:

cin >> arr[10];

I think you are trying to read the whole array in, but that is not possible like that. And if it were (e.g. by overloading >>) it would be using arr instead of arr[10].

You can solve this by overloading >> (though I suspect that to be unnecessarily complex...). Or by reading in with a loop.

CodePudding user response：

It is wrong to use cin to assign values to the entire array. The more common method is to use the for or while structure. I recommend you to read this

Warning C6201 Index '10' is out of valid index range '0' to '9' for possibly stack allocated buffer 'arr'.

The index of the array arr[10] should be arr[0]~arr[9]. About C6385 you should read this document.

char* GetMin(char* a, char* b)
{
    if (strcmp(a, b) < 0) return a;

}

It is best not to use the parameters of the function as the return value. The common method is to define a variable to store the parameters to be returned.

CodePudding user response：

You can't input to an array like

cin >> arr[10];

Instead that inputs a single value into the eleventh element of your ten-element array (leading to undefined behavior).

You need to use a loop to input each element one by one:

for (unsigned i = 0; i < std::size(arr);   i)
{
    std::cout << "Enter input for element " << i   1 << ": ";
    std::cin >> arr[i];
}

On an unrelated note, I recommend you learn more about the standard containers like std::array and std::string. They will make your life as a C programmer much simpler.