Which operator is used to add value to a variable in C++?

The operator used to add value to a variable in C++ is the compound assignment operator, represented as +=. This operator not only adds a specified value to the variable on the left but also assigns the result back to that variable in a single operation. For example, if you have a variable called total and you want to add 5 to it, you can write total += 5;, which is equivalent to total = total + 5;.

Using += improves code readability and conciseness, making it clear that the operation involves an addition followed by an assignment. In addition, it avoids the potential redundancy of repeating the variable name, which can help prevent errors in more complex expressions.

The other options represent different functionalities in C++. The + operator is simply used for addition but doesn’t directly modify the variable. The ++ operator increments the variable by 1 without needing to specify a value explicitly, while the = operator is used for assigning values but does not perform any arithmetic operation. Thus, += is the correct choice for adding a specific value to a variable and updating it simultaneously.