This guide provides detailed instructions on how to resolve the “Expected Unqualified-id Before 'Volatile'” error when using the C language.
What is the “Expected Unqualified-id Before 'Volatile'” Error?
The “Expected Unqualified-id Before 'Volatile'” error usually occurs when attempting to use volatile variables. Volatile is a keyword that informs the compiler that the value of a variable can change unexpectedly. Without this keyword the compiler may optimize away accesses to a variable that could change outside of the code’s control.
How to Fix the Error
The fix for this error depends on the context in which it was encountered.
If the Error Occurs with a Declaration:
If you encounter the “Expected Unqualified-id Before 'Volatile'” error in the context of a variable declaration, make sure that volatile is the first qualifier to appear in the list. A sample declaration is shown below.
Variable_Type Volatile Variable_Name;
If the Error Occurs with an Assignment:
If the error occurs with an assignment, add parentheses around the variable being assigned to. A sample assignment is
(Variable_Name) = Some_Value;
FAQ
Q. What is the “Expected Unqualified-id Before 'Volatile'” Error?
A. The “Expected Unqualified-id Before 'Volatile'” error usually occurs when attempting to use volatile variables. Volatile is a keyword that informs the compiler that the value of a variable can change unexpectedly. Without this keyword the compiler may optimize away accesses to a variable that could change outside of the code’s control.
Q. What is the fix for this error?
A. The fix for this error depends on the context in which it was encountered. If the error occurs in the context of a variable declaration, make sure volatile is the first qualifier to appear in the list. If the error occurs with an assignment, add parentheses around the variable being assigned to.