Question
Answer and Explanation
The <stdexcept> header in C++ (not in C, which doesn't have exception handling as part of the standard language) provides a hierarchy of standard exception classes. One of them is std::logic_error. This class serves as the base class for a family of exception types that represent errors in the internal logic of a program. These kinds of errors are theoretically preventable, meaning that they should ideally not occur during normal execution if your code is written correctly.
Here's a breakdown of what std::logic_error and its derived classes represent:
Key characteristics of logic_error:
- Category: Logic errors indicate that something has gone wrong in the program's design or its internal state.
- Preventable: These errors, in principle, can be avoided with proper program logic and design.
- Base class: std::logic_error itself is typically not thrown directly but is a base class for specific exception types.
- Derived exceptions: Classes derived from std::logic_error describe specific situations where the logic of the program is flawed.
Common exception classes derived from std::logic_error:
- std::invalid_argument: This exception is thrown when a function receives an argument value that it does not expect or cannot handle. For example, if a function expects a positive number but receives a negative number.
- std::domain_error: This exception is thrown when a mathematical function receives an argument that falls outside of the domain for which the function is defined. For instance, trying to take the square root of a negative number might throw a domain_error.
- std::out_of_range: This is thrown when you attempt to access a container (like a string or vector) using an index that is outside of the container's valid range.
- std::length_error: This is thrown when an attempt is made to create a string or other object that would exceed the maximum permissible length.
How to use logic_error classes in practice:
- When you detect a logical error in your code, you should throw an exception from a derived class of std::logic_error. For example:
#include <stdexcept>
int divide(int a, int b) {
if (b == 0) {
throw std::invalid_argument("Division by zero!");
}
return a / b;
}
- Use a try-catch block to handle these exceptions, so your program can respond to the error appropriately instead of crashing.
int main() {
try {
int result = divide(10, 0);
} catch (const std::invalid_argument& e) {
std::cerr << "Error: " << e.what() << std::endl;
}
}
Important Note: Remember that the <stdexcept> header and std::logic_error are part of the C++ standard library, not C. C does not have native exception handling mechanisms like try/catch. When programming in C, you need to use different mechanisms like error codes or signals.
In summary, std::logic_error and its derived classes provide a structured way of representing and handling logic errors in your C++ programs, leading to more robust and understandable code.