The Difference between Structure and Union in Programming

Introduction:

In programming, there are various data types that programmers use to store data in variables. Two of the most commonly used data types are structures and unions. Both structures and unions are used to group variables of different data types, but they differ in several ways. In this article, we will discuss the differences between structures and unions.

What is a Structure?

A structure is a data type in programming that allows the programmer to group variables of different data types under a single name. A structure is defined using the keyword “struct” followed by the name of the structure and a set of curly braces. Inside the curly braces, the programmer can define variables of different data types. The structure is accessed using a variable of the same name as the structure.

What is a Union?

A union is another data type in programming that allows the programmer to group variables of different data types under a single name. A union is defined using the keyword “union” followed by the name of the union and a set of curly braces. Inside the curly braces, the programmer can define variables of different data types. The union is accessed using a variable of the same name as the union.

The Main Differences:

The main difference between structures and unions lies in how the data is stored in memory. In a structure, each variable has its own memory address and takes up as much memory as it needs. In a union, all the variables share the same memory address, and only the largest variable takes up memory. This means that a union takes up less memory than a structure.

Another difference is in how the variables are accessed. In a structure, each variable can be accessed individually using the dot notation. In a union, only the variable that was last assigned data can be accessed.

One other key difference between a structure and union is the way in which the data is stored. In a structure, all the members are stored at different locations and may take up as much memory as they need. In contrast, in a union, all the members share the same memory location to ensure that the union takes up only the necessary memory size.

Conclusion:

In conclusion, both structures and unions are useful data types in programming, but they differ in several ways. The main difference lies in how the data is stored in memory and how the variables are accessed. Programmers should choose the data type that best suits their programming needs to maximize efficiency and reduce memory usage.

Table difference between structure and union

Difference between Structure and Union

Feature	Structure	Union
Definition	A structure is a user-defined data type that can contain variables of different data types.	A union is a user-defined data type that can hold only one value at a time, but of any data type.
Memory Allocation	Each variable in the structure occupies its own memory location, and the memory for the entire structure is the sum of the memory occupied by each variable.	Only one variable in the union can be used at a time, and the memory allocated for the union is the maximum number of bytes that any of its variables require.
Accessing Variables	The variables in a structure can be accessed individually by using the dot (.) operator.	The variables in a union can be accessed individually by using the dot (.) operator, but only one variable can be accessed at a time.
Usage	Structures are used when we want to group different variables of different data types together.	Unions are used when we want to represent a single variable that can take on different values of different data types.