Here’s the key difference between a computer programming function and an API call:
## **Function**
– **Definition**: A block of code that performs a specific task
– **Scope**: Local to your program or application
– **Implementation**: Written by you or provided by libraries/frameworks
– **Location**: Runs within your own process/memory space
– **Example**: `int add(int a, int b) { return a + b; }`
## **API Call**
– **Definition**: A function that provides access to system services, libraries, or external resources
– **Scope**: Accesses external systems or services beyond your local program
– **Implementation**: Provided by operating systems, frameworks, or third-party services
– **Location**: May run in different processes, memory spaces, or even on remote servers
– **Example**: `CreateFile()` (Windows), `open()` (Unix), `glDrawArrays()` (OpenGL)
## **Key Distinctions**
### **Function Characteristics:**
– Local execution within your program
– Direct code implementation
– Can be optimized by compiler
– No network overhead
### **API Call Characteristics:**
– Interface to external services
– May involve system calls or network requests
– Often requires special permissions or setup
– Can have latency and error handling considerations
– May require specific libraries or drivers (like OpenGL drivers)
## **Example Comparison:**
“`c
// Regular function – local to your program
int calculateArea(int width, int height) {
return width * height;
}
// API call – accesses system resources
void* memory = malloc(1024); // System API call
glDrawArrays(GL_TRIANGLES, 0, 6); // OpenGL API call (to graphics driver)
“`
In essence, **all API calls are functions**, but **not all functions are API calls**. API calls are a special category of functions that provide access to external resources or services.
