What type of error occurs when trying to declare a variable with a reserved word?

When attempting to declare a variable using a reserved word, a compile error occurs. Reserved words are part of the programming language's syntax and have predefined meanings, meaning they cannot be used as identifiers, such as variable names, function names, or class names.

During compilation, the compiler checks for syntax errors and verifies that all variables and identifiers conform to the rules of the language. If it encounters a declaration where a reserved word is improperly used as an identifier, it cannot interpret this as valid syntax, leading to a compile error. This prevents the program from compiling successfully, requiring the programmer to modify the code before it can proceed.

Runtime errors, on the other hand, occur while the program is running, indicating issues that arise during execution, such as dividing by zero or accessing an out-of-bounds array index. "Semi-colon expected" refers to a specific type of syntax error where the compiler anticipates a statement termination in the form of a semi-colon but doesn't find one; this is also considered a compile error but not the direct result of using a reserved word. Undefined behavior pertains to situations where a program executes in an unpredictable manner due to logical flaws or accessing invalid memory locations, which is not the case when simply declaring a variable with