In C expression evaluation, consider the statement: a = f1(23, 14) * f2(12/4) + f3(); What is the guaranteed order in which the three function calls f1, f2, and f3 are executed?

Introduction / Context:
Understanding evaluation order in C is critical when expressions contain multiple function calls with potential side effects. Many learners assume that operator precedence dictates evaluation order, but in C precedence only determines grouping, not sequencing. This question tests knowledge of sequence points and unspecified order of evaluation for subexpressions.

Given Data / Assumptions:

• Expression: a = f1(23, 14) * f2(12/4) + f3();
• Each function may have side effects and their relative execution order matters.
• No sequence-point operators (such as &&, ||, or ,) force a particular ordering between these three top-level calls.

Concept / Approach:
Operator precedence and associativity determine how an expression is parsed, not the runtime order in which operands are evaluated. In C, the operands of + and * may be evaluated in any order. Therefore, the calls to f1(...), f2(...), and f3()—which are operands of + and *—have unspecified relative order. A conforming compiler may choose any order, and different optimization levels may produce different valid orders.

Step-by-Step Solution:
Parse the expression based on precedence: (f1(...) * f2(...)) + f3().Recognize that parsing does not impose evaluation sequence.Recall: C leaves the evaluation order of subexpressions of + and * unspecified.Conclude that compilers may call f1, f2, and f3 in any order before performing the arithmetic and assignment.

Verification / Alternative check:
Insert logging side effects in f1/f2/f3 and compile with different compilers or flags; you will observe differing call sequences while still producing a conforming executable.

Why Other Options Are Wrong:

• f1, f2, f3 and f3, f2, f1: Both assert a fixed order that the C standard does not guarantee.
• None of above: Incorrect because the standard explicitly allows the order to vary.

Common Pitfalls:
Assuming precedence equals evaluation order; writing expressions that rely on a particular call order; mixing side effects without sequence guarantees.

Final Answer:
Order may vary from compiler to compiler.