What does the 'static' keyword mean in C++?

• A. Variable cannot be changed
• B. Variable retains value between function calls
• C. Variable can be accessed from anywhere
• D. Variable is initialized once

Answer: (B)

The 'static' keyword in C++ is used to indicate that a variable should maintain its value across multiple function calls. When a variable is declared as static within a function, it is initialized only once, and its value is preserved between invocations of that function. This means that the variable does not get re-initialized each time the function is called, allowing it to retain its value from the previous call.

For instance, if a static variable is used to count how many times a function has been called, that count would correctly represent the total number of calls across all instances of function execution, rather than being reset to zero every time the function starts. This behavior is key in scenarios where you want to remember state information without using global variables or passing values around explicitly.

Other options may suggest different properties or behaviors related to variable scope or accessibility, but they do not accurately reflect the purpose of the 'static' keyword in this context.