Use the EWL_C99 macro to specify whether or not EWL provides a C library that is compliant with the C90 (ISO/IEC 9899-1990) standard or the C99 (ISO/IEC 9899-1999) standard. When compiling a custom version of EWL with EWL_C99 defined as 0, the library conforms to the C90 specification. If EWL_C99 is defined as 1 the library conforms to the C99 specification.