A Comprehensive Guide to C++ if-else Conditional Statements: Fundamentals of Logical Judgment

The if-else conditional statement in C++ is fundamental to program control flow, enabling the execution of different branches based on conditions to achieve "either/or" or multi-condition judgment. Its core syntax includes: the basic structure `if(condition){...} else {...}` for handling two-branch logic; multi-branches extended with `else if`, where conditions are evaluated sequentially with short-circuit execution (subsequent conditions are not checked once a condition is met), as in determining grade levels from highest to lowest. Nested if-else can handle complex logic, such as checking for positive even numbers by nesting parity checks within the positive number branch. When using if-else, note that: conditions must be bool expressions (avoid non-explicit bool conditions like `num`); use `==` instead of `=` for comparison; else follows the "nearest principle"—it is recommended to always use braces to clearly define code block scopes; multi-condition judgments require reasonable ordering to avoid logical errors. Mastering these concepts allows flexible handling of branch logic and lays the foundation for advanced content like loops and functions.