initialized and declared extern

When a variable is declared as extern, it means that the variable is defined elsewhere in the program. This declaration allows the variable to be used in multiple source files without causing a linker error.

To initialize and declare an extern variable, you need to perform the following steps:

1. Define the extern variable in a header file: Create a header file (e.g., "example.h") and declare the variable using the extern keyword. For example:

   // example.h
   extern int myVariable;
   

2. Include the header file in the source files where you want to use the extern variable. For example:

   // main.c
   #include "example.h"
   
   int main() {
       // Use the extern variable
       myVariable = 10;
       // Rest of the code
       return 0;
   }
   

3. Define the extern variable in one of the source files: Choose one of the source files (e.g., "example.c") and define the extern variable without the extern keyword. For example:

   // example.c
   int myVariable; // Definition of the extern variable
   

By following these steps, you can initialize and declare an extern variable in your program. Remember that the variable should be defined in only one source file to avoid multiple definitions and linker errors