What will the following C code print? int value, x, y; value = (x = 10, y = 5,…

Concept. Used as an operator, the comma in C is a sequencing operator: in an expression a, b the left operand is evaluated first and its value is discarded, and the value and type of the whole expression are those of the rightmost operand. Each comma is a sequence point, so every side effect of one operand is complete before the next operand begins.

Application.

1. The parentheses in (x = 10, y = 5, x + y) enclose one comma expression with three operands, so the operands are evaluated strictly left to right.

2. The first operand x = 10 is evaluated: it stores 10 in x. The value it produces is discarded at the comma.

3. The second operand y = 5 is evaluated: it stores 5 in y. Its value is discarded at the next comma.

4. The third and rightmost operand x + y is evaluated with the stored values: 10 + 5 = 15. Because it is the rightmost operand, 15 is the value of the whole parenthesised expression.

5. That value is assigned to value, so value holds 15 and printf("Value = %d", value) writes Value = 15.

Cross-check. The snippet is well-formed C: the commas in the declaration int value, x, y; are declarator separators, the commas inside the parentheses form a comma expression, and the %d conversion specifier is paired with an int argument, so nothing here is a constraint violation. Treating only the first assignment as the expression’s value would give 10, and treating only the second as its value would give 5; both readings ignore that a comma expression takes the value of its last operand, which is why the sum 15 is what reaches value.