Question

to add a value 1 to variable x, you write ______.
a ( x := 1; )
b ( x = x + 1; )
c ( x += 1; )
d ( 1 + x = x; )
e ( x = 1 + x; )

Explanation:

• Option A: x := 1; assigns 1 to x, not adding 1 to its current value.
• Option B: x = x + 1; (in programming, often x = x + 1 or with specific syntax) takes the current value of x, adds 1, and assigns back to x.
• Option C: x += 1; is a shorthand (in many programming languages) for x = x + 1, which adds 1 to x.
• Option D: 1 + x = x; is an invalid assignment (left - hand side is not a variable lvalue in the context of assignment to change x's value).
• Option E: x = 1 + x; is equivalent to x = x + 1 (since addition is commutative), it takes the current x, adds 1, and assigns to x.

In programming, to add 1 to a variable x, the valid ways are x = x + 1;, x += 1; (shorthand), or x = 1 + x; (since addition is commutative). Options B, C, E are correct in the context of variable increment (depending on the programming language's syntax for assignment and arithmetic operations). If we consider common programming constructs:

• x = x + 1 is a basic way to increment.
• x += 1 is a shorthand increment operator.
• x = 1 + x is also a valid way as addition is commutative and it will add 1 to the original value of x and re - assign.

Answer:

B. \( x = x + 1; \), C. \( x += 1; \), E. \( x = 1 + x; \)