Question

When you assign a value to a variable, what happens to any value that is already stored in the variable?

Short answer

Answer: When a new value is assigned to a variable that already contains a value, the old value is overwritten by the new value and is no longer available in memory.

Step-by-step solution

Understanding Variables

A variable is a symbolic name given to a storage location in memory. It is used to store and manipulate data throughout the program. When a value is assigned to a variable, it is stored in the memory location associated with that variable's name.

Initial Value Assignment

When a variable is first assigned a value, it stores that value in its associated memory location. For example, let's assign a value of 5 to a variable named 'x'. x = 5 Now, the variable 'x' stores the value 5 in its memory location.

Reassignment of Value for a Variable

When a new value is assigned to a variable that already has a value, the new value replaces the initial value stored in the memory location. For example, let's assign a new value of 10 to the variable 'x'. x = 10 With this assignment, the value 10 replaces the previous value 5 which was stored in the memory location associated with the variable 'x'.

Outcome of Reassignment

After a new value is assigned to a variable, the old value is discarded, and the memory location now holds the new value. In our example, after the reassignment, the variable 'x' no longer holds the value 5; instead, it now contains the value 10. The initial value (5) is lost as it has been overwritten by the new value (10) in the memory. In conclusion, when a new value is assigned to a variable that already contains a value, the old value is overwritten by the new value and is no longer available in memory.

Key concepts

Data Manipulation

Data manipulation in programming refers to the process of handling data by performing operations on it to achieve a desired outcome. This typically involves creating, reading, updating, or deleting data. In the realm of variables, manipulation is most commonly associated with updating the content that a variable holds.

For instance, if we have a variable 'score' with an initial value of 50, performing an operation such as 'score = score + 10' is a basic example of data manipulation. Here, we are taking the current value of 'score', adding 10 to it, and then storing the new value back into 'score'. The original value is modified to reflect the result of our operation.

Memory Storage in Programming

Memory storage in programming refers to the way that data is stored in a computer's memory for use by programs. When a variable is defined, the programming language's compiler or interpreter allocates a particular memory location for that variable.

This location is where the variable's value will be stored, and it is uniquely identified by an address. Variables can be thought of as labels or names for these storage locations. Understanding how and where data is stored helps programmers to optimize memory usage and create efficient software. When the value of a variable changes, what is actually happening is that the contents of the storage location that the variable refers to are being updated.

Variable Reassignment

Variable reassignment is a fundamental concept in programming that changes the value stored in the variable's memory location. It is common to reassign variables multiple times throughout a program as the state of the program changes.

For example, after declaring a variable 'total' with an initial value of 0, you might reassign it several times within a loop that adds numbers to it, like this: 'total = total + number'. Each time 'total' is reassigned, the memory storage at the variable's address is updated to hold the new value. It's important to note that after reassignment, the old value is completely replaced and cannot be recovered unless it was stored or used elsewhere prior to reassignment.