53. Try and catch block

Catch – a program that utilises an exception handler to catch an Exception. It is added to the part of a program where you need to deal with the error.
Try – the try block recognises the code block for which certain exceptions will be enacted. It ought to be followed by one/more catch blocks.

How try-catch in c++ works?

Try catch in c++ is defined as the exception that is raised in the code block.The exception will be gotten by a strategy utilising try and catch keywords. The try/catch block should encompass code that may throw an exception. Such code is known as protected code.

Try/catch Syntax:

The try/catch takes this syntax:

try {
// the protected code
} catch( Exception_Name exception1 ){
// catch block
} catch( Exception_Name exception2 ){
// catch block
} catch( Exception_Name exceptionN ){
// catch block
}

Apart from the fact that we have one try statement, we can have many catch statement.
The ‘ExceptionName’ is the name of the Exception for being caught.
The exception1, exception2, exception3 and exceptionN are your defined names for referring to the exceptions.

Try/catch Example 1:

#include<iostream>
#include<vector>
using namespace std;
int main(){
vector<int> vec;
vec.push_back(0);
vec.push_back(1);
// access the third element, that doesn't exist
try{
vec.at(2);
}
catch (exception& ex)
{
cout << "Exception occurred!" << endl;
}
return 0;
}

Output:

Exception Occurred!

Try/catch Code Explanation:

Include the ‘iostream’ header file in the program to utilise its functions.
Include the ‘vector’ header file in the program to utilise its functions.
Then include the ‘std namespace’ in the program to its classes without calling it.
Call the main() function. The program logic ought to be added inside its body.
Create a vector name vec to store integer data.
Add component 0 to the vector named vec.
Add component 1 to the vector named vec.
Utilise the try statement to catch an exception. The { marks the start of the body try/catch block. The code added inside the body will turn into the protected code.
Attempt to access the element stored in index 2 (third element) of the vector named vec. This component doesn’t exist.
End of the body of the try/catch block.
Catch the exception. The returned error message will be put away in the variable ex.
Print out some message on the comfort if the exception is caught.
End of the body of the catch block.
The program should return a value upon fruitful execution.
End of the main() function body.

How to use try-catch in c++?

Try-catch is an important keyword while performing exceptional conditions.
In the Try block, the “throw” keyword throws an exception when the code detects a problem, which lets us create a custom error.
Now “catch” keyword comes into a picture i.e. “catch” keyword allows you to define a block of code to be executed if an error occurs in the try block.

How do you catch exceptions in C++?

To catch exceptions, a part of the code is kept underinspection. This is done by closing that part of the code in a try-block. When an exceptional circumstance arises within that block, an exception is thrown and an exception handler takes control over the program.