g++ 编译错误 请教

ooko

g++   -g -DHAVE_CONFIG_H -I/usr/include/mysql -I. -D__cplusplus -D_REENTRANT -D_
_JAVACLIENT__ -D_THREAD_SAFE -pthread -c  -fPIC -DPIC  -I/usr/include -static -p
thread     -o login1.o -c login1.cpp
login1.cpp: In function `int main(int, char **)':
login1.cpp:104: warning: default argument of negative value `-1' to `long unsign
ed int'
login1.cpp:110: warning: default argument of negative value `-1' to `long unsign
ed int'
login1.cpp: In function `class YString comm39(const class YString &, const class
YString &, const class YString &, const class YString & = ""':
login1.cpp:912: warning: initialization to `char *' from `const char *' discards
const
login1.cpp:913: warning: passing `char *' as argument 1 of `URLDecode(unsigned c
har *)' changes signedness
login1.cpp:955: warning: passing `const YString' as `this' argument of `class YS
tring & YString:perator =(const class YString &' discards const
login1.cpp:956: warning: passing `const YString' as `this' argument of `class YS
tring & YString:perator =(const class YString &' discards const
make: *** [login1.o] Error 1

这段错误是什么意思
为什么会出现
value `-1' to `long unsigned int'


相关代码
          //g_applog->;write("[main]write "+loginMessage+" to "+fifoLoginMessage.getName());
          if(fifoLoginMessage.write(loginMessage)!=0)
                  {
             YErr::show(g_err.ErrDescription);
             PrintErrorMessagePage("[40001]内部错误。";
             return -1;
          }


还有就是 g++2.91 和2.95的 容错是不是有差别?
在2.91上虽然提示有错但仍可通过
2.95上就终止了继续编译