The difference between declarative and imperative programming lies in how the program specifies what to do versus how to do it:
Imperative Programming
Focus: Describes how to achieve a result.
Approach: The programmer specifies the step-by-step instructions or operations the computer must perform.
Key Features:
Uses explicit control flow (e.g., loops, conditionals).
Emphasizes algorithms and state changes.
Examples: C, Java, Python (when using loops and control structures).
Analogy: Like giving a recipe with exact steps to follow.
Example (Finding the sum of numbers in a list):
C Copy code
int sum = 0;
for (int i = 0; i < n; i++) {
sum += array[i];}
Declarative Programming
Focus: Describes what result is desired, not how to achieve it.
Approach: The programmer specifies the desired outcome, leaving the execution details to the underlying system.
Key Features:
Abstracts away the control flow and low-level details.
Often avoids explicit state changes.
Examples: SQL, HTML, Prolog, and functional programming styles in languages like Haskell or Python (e.g., using map, filter).
Analogy: Like stating, “I want a cake,” without specifying how to bake it.
Example (Finding the sum of numbers in a list):
python
Copy code
sum = sum(array)
Key Differences
Aspect Imperative Declarative
Focus How to do it What to do
Control Flow Explicitly defined Abstracted
State Typically mutable Often immutable
Examples C, Java, Python (with loops) SQL, Prolog, Haskell
In summary, imperative programming is about giving instructions, while declarative programming focuses on describing the goal.