Did you just simply edit that header file and then try to recompile your program? If so, then that is to be expected, since wide support probably was not compiled into the compiler. You're probably going to have to rebuild your compiler with support for wide characters so that these functions can get defined. Thanks, Lyle -----Original Message----- From: gcc-help-owner@xxxxxxxxxxx [mailto:gcc-help-owner@xxxxxxxxxxx] On Behalf Of suresh.t@xxxxxxxxxxx Sent: Monday, January 10, 2005 3:15 AM To: gcc-help@xxxxxxxxxxx Subject: wstring and wchar_t usage with gcc hi, My code using wstring and wchar_t does not compile. I realized that "_GLIBCPP_USE_WCHAR_T" was undefined in c++config.h file and defined it. It cleared the first error ( i guess) but resulted in further errors like below from the cwchar header. /gcc/3.2.1/include/c++/3.2.1/cwchar:137: `btowc' not declared /gcc/3.2.1/include/c++/3.2.1/cwchar:142: `fwide' not declared /gcc/3.2.1/include/c++/3.2.1/cwchar:143: `fwprintf' not declared /gcc/3.2.1/include/c++/3.2.1/cwchar:144: `fwscanf' not declared /gcc/3.2.1/include/c++/3.2.1/cwchar:147: `mbrlen' not declared Can someone tell me what needs to be done? Thanks