When using gcc, we often encounter errors such as expected specifier qualifier list before sth. Specifiers refer to words such as void, char and struct foo; Qualifiers are keywords like const and volatile. If a word is used before it is defined, this kind of error will appear. You can define it through typedef and use it later

here is an example and an optional solution

Error instance:

Solution 1:

Solution 2:

Similar Posts:

• sorry, unimplemented: non-trivial designated initializers not supported
• How to Solve Const variable assignment Error
• [Solved] Undefined reference_G++ _GLIBCXX_USE_CXX11_ ABI compilation error: STD:: Basic_String and STD::__cxx11::basic_String cannot match
• error LNK2038: mismatch detected for ‘RuntimeLibrary’: value ‘MDd_DynamicDebug’ does not match value ‘MTd_StaticDebug’
• [How to Solve] dereferencing pointer to incomplete type
• Solution to the problem of “TypeError: Assignment to constant variable”
• invalid conversion from ‘void* (*)()’ to ‘void* (*)(void*)’
• deprecated conversion from string constant to char*
• Analysis of Android sleep wake mechanism — wake_ lock
• [Solved] undefined reference to `cv::imread(std::string const&, int)’