> Carry: "if (x + y < x)" compiles to code that uses the carry flag. If x and y are signed, you're relying on UB, which the compiler might optimize out. > "if

> Carry: "if (x + y < x)" compiles to code that uses the carry flag. If x and y are signed, you're relying on UB, which the compiler might optimize out. > "if ((int32_t) (x + y) < 0)" compiles to code that uses the overflow flag. Again, which type are x and y? If signed, this code is UB. If unsigned, then the result of conversion to int32 may not fit into int32, in which case the result is implementation-defined, or and implementation-defined signal is raised. Portable? Right.