Essential Concepts in Programming and Networking: Pointers, LAN/WAN, Data
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Understanding Pointers in Programming
A pointer is a variable whose value is the memory address of another variable. Like any variable or constant, you must declare a pointer before you can work with it.
C++ Pointer Example
#include <iostream>
using namespace std;
int main ()
{
int var = 20; // Actual variable declaration.
int *ip; // Pointer variable declaration.
ip = &var; // Store address of var in pointer variable.
cout << "Value of var variable: " << var << endl;
// Print the address stored in ip pointer variable
cout << "Address stored in ip variable: " << ip << endl;
// Access the value at the address available in pointer
cout << "Value of *ip variable: " << *ip << endl;
return 0;
}LAN vs. WAN: Key Differences in Network Types
| Feature | LAN (Local Area Network) | WAN (Wide Area Network) |
|---|---|---|
| Stands for | Local Area Network | Wide Area Network |
| Coverage Area | Covers local areas only (e.g., homes, offices, schools, or a group of buildings). | Covers large geographic areas (e.g., cities, states, nations). |
| Definition | A computer network covering a small geographic area. | A computer network that covers a broad area, where communication links cross metropolitan, regional, or national boundaries over a long distance. |
| Speed (Typical) | High speed (e.g., up to 1000 Mbps) | Lower speed (e.g., up to 150 Mbps) |
| Data Transfer Rates | LANs have a high data transfer rate. | WANs have a lower data transfer rate compared to LANs. |
Data vs. Information
Defining Data
Data is raw, unorganized facts that need to be processed. Data can be something simple and seemingly random and useless until it is organized.
Example: Each student's test score is one piece of data.
Defining Information
When data is processed, organized, structured, or presented in a given context so as to make it useful, it is called information.
Example: The average score of a class or of the entire school is information that can be derived from the given data.
Etymology
- Data: Comes from the singular Latin word datum, which originally meant "something given." Its early usage dates back to the 1600s. Over time, "data" has become the plural of datum.
- Information: An older word dating back to the 1300s, with Old French and Middle English origins. It has always referred to "the act of informing," usually in regard to education, instruction, or other knowledge communication.