cc -pthread -Wall -Wextra -Werror=implicit-function-declaration wchar/fputws.c -o wchar/fputws -D_GNU_SOURCE -D_BSD_SOURCE -D_ALL_SOURCE -D_DEFAULT_SOURCE -lm -lpthread -lrt -lintl -liconv wchar/fputws.c: In function ‘main’: wchar/fputws.c:12:14: error: implicit declaration of function ‘fputws’; did you mean ‘fputs’? [-Wimplicit-function-declaration] 12 | if ( fputws(L"foo", fp) == -1 ) | ^~~~~~ | fputs wchar/fputws.c:19:15: error: implicit declaration of function ‘fgetws’; did you mean ‘fgets’? [-Wimplicit-function-declaration] 19 | if ( !fgetws(buf, sizeof(buf)/sizeof(buf[0]), fp) ) | ^~~~~~ | fgets