extern Keyword in C – Declaration, Definition, and Multi-File Programs

Posted on October 14, 2011July 12, 2026 by Sandeepa Nadahalli

The extern keyword in C declares that a variable or function exists — but is defined somewhere else. It tells the compiler “trust me, this symbol is defined in another translation unit; the linker will resolve it.” Understanding extern is essential for any multi-file C program, and confusing declaration with definition is one of the …

C Program to Demonstrate global and internal variables.

Posted on October 10, 2011June 29, 2026 by Sandeepa Nadahalli

Variable scope controls where in a program a variable can be accessed. In C, a variable’s scope is determined by where it is declared: variables declared outside all functions have file scope (global), while variables declared inside a function or block have block scope (local). A third kind — static local variables — persist between …