课堂上的质数程序在实际操作时,组建时出现“--------------------Configuration: zhishu - Win32 Debug--------------------Linking...zhishu.obj : error LNK2001: unresolved external symbol _soqrtDebug/zhishu.exe : fatal error LNK1120: 1 unresolved externals执行 link.exe 时出错.zhishu.exe - 1 error(s), 0 warning(s)”,,编译是正确的。。。这是怎么 了?