Arizona State University (ASU) CSE100 Principles of Programming with C++ Midterm 1 Practice Exam

The `const` keyword in C++ is used to indicate that a variable's value is constant and cannot be modified after it has been initialized. This means that once a value is assigned to a variable declared with `const`, any attempt to change this value will result in a compilation error. This feature is useful for various programming scenarios, such as defining constants that should not change, helping to prevent accidental modification of values throughout a program, and increasing code readability by making the intent clear that certain variables are meant to remain unchanged.

Using `const` can also improve program safety and maintainability, as it allows programmers to enforce that certain values remain fixed for the duration of their scope. This plays a significant role in ensuring that the logic of the program is followed consistently, as any attempt to change a `const` variable will be caught by the compiler, highlighting potential logical errors early in the development process.

In contrast, the other options do not accurately represent the effects of using `const`. For example, a `const` variable cannot be modified after initialization (which is why the correct answer emphasizes this point), it does not dictate visibility within its scope or restrict usage to header files specifically.