Programs vs. Scripts

What is a Program ? What is a Script ? What are the key differences between Programs and Scripts ?

Let's understand it step by step!

What is a Program ?

A program is a set of instructions written by a programmer in a specific programming language. Before it can run, the program is converted (compiled) into machine code, a language the computer's processor understands. This compilation is done using a compiler. Once compiled, the program becomes a standalone executable file like .exe for Windows. After compilation, the program can run directly on the computer as long as the required operating system and platform (hardware/software combination) are available.

Example: A video game written in C++ is compiled into an executable file. You can run it without needing the C++ compiler again, but it will only work on platforms it was designed for Windows or macOS.

What is a Script ?

A script is set of instruction written in a scripting language. Scripts are not converted into machine code. Instead, they are read and executed line-by-line by an interpreter. The interpreter acts as a middleman, translating the script into something the computer can understand. Without the interpreter, the script cannot run. Once you have the interpreter installed, the same script can run on different platforms (Windows, macOS, Linux) without changes because the interpreter handles platform-specific details.

Example: A Python script can be run on any computer as long as Python is installed.

Let's make it clearer by using real world example.

• You are making pizzas and freezing them. Any customer can purchase the pizza and bake it in their own oven without your presence. Customer needs only an oven to eat it. We can consider the frozen pizza as a (program) and the chef as a (compiler) and the process of pre-cook and freeze as (translation) and the oven as a (specific platform).
• The chef has a recipe. Chef is presenting to explain the instructions to you line by line. However, you can cook the recipe in any kitchen as long as you have the chef. In here, we can consider the recipe as a (script) and the chef as an (interpreter) and the any kitchen as a (cross-platform).

Advantages of Programs

1. Performance: Compiled programs are faster because they are directly executed in machine code.
2. Standalone: Once compiled, no additional tools are required to run.
3. Optimized for Specific Platforms: Programs can be fine-tuned for specific hardware or operating systems.
4. Security: Source code is not exposed in the executable, making it harder to reverse-engineer.

Disadvantages of Programs

1. Platform Dependency: Compiled programs often need separate versions for different platforms.
2. Complex Development: A compiler analyzes the entire program and displays all errors after compilation, preventing code from compiling if it contains mistakes.
3. Inflexibility: Changes in the code require recompilation and redistribution of the executable.
4. Development Tools: Requires compilers, which can be complex and resource-intensive.

Advantages of Scripts

1. Cross-Platform: Scripts can run on any system with the appropriate interpreter.
2. Ease of Development: No compilation needed; changes can be tested immediately.
3. Simplicity: Ideal for smaller tasks, automation, and quick prototypes.
4. Flexibility: Easier to modify and debug compared to compiled programs.

Disadvantages of Scripts

1. Performance: Slower execution since scripts are interpreted line-by-line.
2. Dependency on Interpreters: Requires the correct interpreter to be installed on the target system.
3. Security Risks: Source code is exposed, making it easier to reverse-engineer or modify.
4. Scalability: Less suitable for large-scale applications due to performance constraints.