Key Differences
| Aspect | Global Variable | Static Variable |
|---|---|---|
| Scope | Accessible throughout program | Limited to file, function, or class scope |
| Visibility | Shared across files (extern) |
Restricted to declaring scope |
| Lifetime | Entire program duration | Entire program duration |
Example Code
Global Variable
// globals.cpp
int globalVar = 42; // Global variable
// main.cpp
#include <iostream>
extern int globalVar; // Declaration for the global variable from another file
void modifyGlobal() {
globalVar++; // Accessible across files
}
int main() {
modifyGlobal();
std::cout << "Global Variable: " << globalVar << std::endl; // Prints: 43
return 0;
}
File-Scope Static Variable
#include <iostream>
static int staticVar = 10; // File-scope static
void modifyStatic() {
staticVar++; // Accessible only within this file
}
int main() {
modifyStatic();
std::cout << "Static Variable: " << staticVar << std::endl; // Prints: 11
return 0;
}
Function-Scope Static Variable
#include <iostream>
void counter() {
static int count = 0; // Retains value across calls
count++;
std::cout << "Count: " << count << std::endl;
}
int main() {
counter(); // Prints: 1
counter(); // Prints: 2
return 0;
}
Source link
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