What's the difference between a compile-time error, a runtime error, and a logic error?

A compile-time error is something the compiler catches before producing an executable, missing semicolons, type mismatches, undeclared variables. No binary is produced, so the program can't be run at all. A runtime error happens after a successful compile, when the program is actually executing, null pointer dereference, divide by zero, array out-of-bounds, stack overflow. The compiler couldn't predict it because it depended on values not known until runtime. A logic error is the hardest kind: the program compiles, runs without crashing, and produces output, but the output is wrong. Off-by-one in a loop, the wrong operator, a misplaced condition. Compile-time errors get caught by the compiler, runtime errors get caught by sanitizers or by crashing, but logic errors require testing to find, automated tests, sanity checks on output, or manual inspection of results.