> ## Documentation Index > Fetch the complete documentation index at: https://docs.syntblaze.com/llms.txt > Use this file to discover all available pages before exploring further. # C Conditional The `?:` operator, formally known as the conditional operator, is the only ternary operator in the C programming language. It evaluates a controlling scalar expression and, based on whether the result compares unequal to zero, evaluates and yields the value of exactly one of two subsequent expressions. ```c theme={"dark"} logical_OR_expression ? expression_if_true : expression_if_false ``` ## Evaluation Semantics 1. **Control Expression:** The first operand (`logical_OR_expression`) must have a scalar type (arithmetic or pointer). It is evaluated first. 2. **Sequence Point:** There is a strict sequence point immediately after the evaluation of the first operand. All side effects of the first operand are guaranteed to be complete before any further evaluation occurs. 3. **Short-Circuit Evaluation:** The operator guarantees mutually exclusive evaluation of the second and third operands. If the first operand evaluates to a non-zero value, only `expression_if_true` is evaluated. If the first operand evaluates to zero, only `expression_if_false` is evaluated. The unevaluated operand produces no side effects. ## Type Resolution The type of the result yielded by the conditional operator is determined at compile-time by the types of the second and third operands, regardless of which expression is evaluated at runtime. The compiler determines the common type using the following rules: * **Arithmetic Types:** If both the second and third operands have arithmetic types, the *usual arithmetic conversions* are applied to determine a common type. For example, if one is `int` and the other is `double`, the result type of the entire expression is `double`. * **Structure and Union Types:** If both operands have compatible structure or union types, the result has that compatible structure or union type. * **Void Types:** If both operands are `void` expressions, the result is a `void` expression. * **Pointer Types:** * If both are pointers to compatible types, the result is a pointer to the composite type, carrying the combined type qualifiers (e.g., `const`, `volatile`) of both operands. * If one operand is a pointer and the other is a null pointer constant (like `NULL` or `0`), the result type is the type of the pointer operand. * If one operand is a pointer to an object type and the other is a pointer to `void`, the result is a pointer to an *appropriately qualified* version of `void`. The resulting pointer type combines the type qualifiers of both the object pointer and the `void` pointer. ## Value Category In C, the result of the conditional operator is always an **rvalue** (a value that does not have a memory address identifiable by the programmer). Unlike in C++, you cannot use the C conditional operator on the left side of an assignment operator. ```c theme={"dark"} /* Valid C: Yields an rvalue */ int result = (x > y) ? x : y; /* Invalid C: Attempting to use the result as an lvalue */ ((x > y) ? x : y) = 10; /* Compilation error */ ```

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