What are uninitialized global variables in Linux?

In the Linux environment, uninitialized global variables will be automatically initialized to either zero value or null value, depending on the variable’s data type.

Here are default initial values for some common data types:

Global variables of integer types (such as `int`, `long`, etc.) will be initialized to 0.

Global variables of floating-point types (such as `float`, `double`, etc.) will be initialized to 0.0.

Global variables of character type (such as `char`) will be initialized as empty character `’\0’`.

Global variables of pointer type will be initialized as NULL pointer, which means the address is 0.

Global variables of structure types will recursively initialize their member variables to default values of the corresponding type.

Please note that these initialization rules only apply to static variables at the global scope and static variables at the file scope. For automatic variables within functions (local variables), they do not have a default initialization value and must be manually initialized before use.

If you have special requirements, you can manually assign the desired initial value to global variables to override the default behavior.