Exceptions
From Vaddina.com
Exceptions Vs.Return values
| try and catch | The good old return |
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Constructors and destructors does not return values. Moreover they naturally throw exceptions. Hence ignoring this and trying to accomplish something with error codes is not quite advisible. |
Cannot be used, in their original sense, in Constructors and Destructors. However, the constructors and destructors can be passed references or pointers, or a member variable can be used to save the result of an operation. |
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They can be used over function boundaries. Thus when a function raises an exception, it can be handled anywhere in the parent functions where the function in question is called. Example void fn1() { cout << “function – 1” << endl; try { fn2(); } catch(int i) {cout << “ exception “ << I; } cout << “In function – 1.1”; } void fn2() { cout << “In function – 2” << endl; fn3(); cout << “In function – 2.2; } void fn3() { cout << “In function – 3; throw 3; cout << “In function – 3.3; } int main() { fn1(); cout << “I am in Main” << endl; } |
Such a technique is not possible. The parent function which called the error generating function must handle the exception, based on the returned error code. |
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One of the primary use of exception handling with tryand catch is explained in the following example. // Class storing information of an exception class CException { public: char* message; CException(char* m) { message = m }; Report(); } try{ CalculateValue(); SetValue(); GetValue(); } catch (CException &ce) { ce.Report(); } In the example above we can observe that any exceptions of the type CException thrown by three functions can be caught by a single catch block. Such type of mechanism eventhough possible to implement using simple return codes, may need several if statements, which is often hard to read and maintain. | |
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The program execution does not terminate unless explicitly stated. |
