linkage determines whether multiple declarations of an identifier (such as a variable or function) refer to the same entity or different entities across translation units or within the same translation unit.

When you declare a variable inside a function, it has no linkage. That means each declaration creates a completely separate variable in the same function scope, which is not allowed.

If myVariable is meant to be the same across multiple lines inside the function, remove the second declaration and declare it at file scope (outside the functions.)