Exception Handling in C++

Exception Handling in C++ is a mechanism used to handle runtime errors and abnormal conditions, allowing a program to continue execution smoothly even in the presence of errors.

• Handles abnormal conditions that occur during program execution.
• Helps maintain program stability by preventing unexpected program termination.

Basic try-catch Example

The try block contains code that might throw an exception, while the catch block handles the exception if it occurs.

#include <iostream> 
using namespace std; 
int main() 
{ 
    int n = 10; 
    int m = 0; 
    
    try { 
        if (m == 0) 
        throw "Division by zero"; 
        cout << "Answer: " << n / m; 
        
    } 
    catch (const char* msg) {
        cout << "Error: " << msg; 
        
    } 
    return 0; 
    
}

Error: Division by zero

Internal Working of try-catch Block

When an exception occurs:

• The runtime executes code inside the try block.
• If an exception is thrown, the remaining code inside the try block is skipped.
• The runtime searches for a matching catch block.
• If found, the exception is handled.
• If no matching handler is found, terminate() is called.
• During this process, stack unwinding occurs and local objects are destroyed automatically.

Note: If an exception is not handled, the program terminates abruptly.

throw Keyword

The throw keyword is used to explicitly throw an exception.

#include <iostream> 
using namespace std; 
void checkAge(int age) { 
    
    if (age < 18) 
        throw "Age must be 18 or above"; 
    
} 

int main() {
    
    try { 
        checkAge(15); 
        
    } 
    catch (const char* msg) { 
        cout << msg; 
        
    } 
    return 0; 
    
}