The language **C** does not provide direct support for exception handling.

This means that there is no mechanism to trap errors. In some cases, the code may continue to execute with errors.

# Details

In such situations, the *compiler's* behavior becomes unpredictable, or **`undefined`**. 


Anything can happen, which may include the following:

1. **Program Crash:** The entire program may crash citing any error as the reason

2. **Unpredictable Results:** The program may generate incorrect or garbage output

3. **Data Corruption:** The compiler may corrupt data which could lead to several other problems

# Code

Let's look at an example for `undefined` behavior:

#include <stdio.h>
#include <stdlib.h>

int main(){

  // We will try to access arr[5] which is out of bounds
  int arr[5] = {0, 1, 2, 3, 4};

  int i = 0;
  for(; i <= 5; i++)
    printf("%d\n", arr[i]); 

  return 0;
}

In the above case, we try to access the 5th element in the array, which is **out of bounds**.

The compiler continues execution, regardless of the error. As a result, the 5th output is **`undefined`**. 

There is no way to predict what we will get as our 5th output.

>The tolerance for **`undefined`** behavior in **C** allows for faster compilation of code due to fewer checks.



What is undefined behavior in C?

Details

Code