What characterizes a compiler error?

A compiler error is indeed characterized as a syntax error that prevents code execution. When code is written, it needs to adhere to the rules of the programming language's syntax. If there are deviations from these rules—such as missing semicolons, incorrect brackets, or improperly structured statements—the compiler will identify these issues before the program can run. This ensures that only code that is syntactically correct is executed, helping to avoid potential issues at runtime.

The nature of compiler errors is unique; they occur during the compilation process when the source code is translated into machine code. Since the code contains errors, the compiler cannot produce an executable file, which is why execution is halted until these errors are resolved. Addressing these errors is crucial for developers, as it ensures that the code is fundamentally sound before testing it in a runtime environment.

In contrast, the other options describe different scenarios: warnings merely suggest potential problems without halting execution, runtime errors occur during execution and relate to problems that only become apparent when the program is running, and logical flaws pertain to the design or algorithm of the program but do not manifest as syntax errors.