在VC++里，一个变量已赋值，想在这个赋值语句之后将这个变量的值写到规定路径的相应
的TXT文件里，要求是这个变量不停被赋予新的值，然后这个值就依次写到到TXT文件里，
并且上次的值不能被这次的值覆盖。
由于急用
恳请达人帮忙写个程序段，谢谢

首先判断这个文件夹是否创建，如果没创建，就创建后写入，反之就用追加方法打开，这样就可以接着上次结束处，接着写入新数据，例如
FILE file;
file=fopen("c:\\test.txt","r");
if  ( file == NULL )
{
   //没有创建文件，则创建文件
    file=fopen("c:\test.txt",w");
   //写入数据
     ....
   fclose(file);
}
else
{
    //表示创建了，则关闭后，在用追加方式写入
    fclose(file);
   file=fopen("c:\test.txt",a");
   //写入数据
     ....
   fclose(file);
}

我把程序嵌入后,有编译错误.
于是将代码改为:
FILE file;
file=fopen("c:\\test.txt","r");
if  ( file == NULL )
{
   //没有创建文件，则创建文件
    file=fopen("c:\test.txt","w");
   //写入数据
     file.write (strtemp);
   fclose(file);
}
else
{
    //表示创建了，则关闭后，在用追加方式写入
    fclose(file);
   file=fopen("c:\test.txt","a");
   //写入数据
    file.write (strtemp);
   fclose(file);
}

发现还有编译错误
错误如下:
--------------------Configuration: CommWizard - Win32 Debug--------------------
Compiling...
CommWizardDlg.cpp
E:\激光器驱动\温控电路相关资料\串口精灵源代码\CommWizardDlg.cpp(294) : error C2679: binary '=' : no operator defined which takes a right-hand operand of type 'struct _iobuf *' (or there is no acceptable conversion)
E:\激光器驱动\温控电路相关资料\串口精灵源代码\CommWizardDlg.cpp(295) : error C2678: binary '==' : no operator defined which takes a left-hand operand of type 'struct _iobuf' (or there is no acceptable conversion)
E:\激光器驱动\温控电路相关资料\串口精灵源代码\CommWizardDlg.cpp(298) : error C2679: binary '=' : no operator defined which takes a right-hand operand of type 'struct _iobuf *' (or there is no acceptable conversion)
E:\激光器驱动\温控电路相关资料\串口精灵源代码\CommWizardDlg.cpp(300) : error C2039: 'write' : is not a member of '_iobuf'
        d:\microsoft visual studio\vc98\include\mbstring.h(92) : see declaration of '_iobuf'
E:\激光器驱动\温控电路相关资料\串口精灵源代码\CommWizardDlg.cpp(301) : error C2664: 'fclose' : cannot convert parameter 1 from 'struct _iobuf' to 'struct _iobuf *'
        No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called
E:\激光器驱动\温控电路相关资料\串口精灵源代码\CommWizardDlg.cpp(306) : error C2664: 'fclose' : cannot convert parameter 1 from 'struct _iobuf' to 'struct _iobuf *'
        No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called
E:\激光器驱动\温控电路相关资料\串口精灵源代码\CommWizardDlg.cpp(307) : error C2679: binary '=' : no operator defined which takes a right-hand operand of type 'struct _iobuf *' (or there is no acceptable conversion)
E:\激光器驱动\温控电路相关资料\串口精灵源代码\CommWizardDlg.cpp(309) : error C2039: 'write' : is not a member of '_iobuf'
        d:\microsoft visual studio\vc98\include\mbstring.h(92) : see declaration of '_iobuf'
E:\激光器驱动\温控电路相关资料\串口精灵源代码\CommWizardDlg.cpp(310) : error C2664: 'fclose' : cannot convert parameter 1 from 'struct _iobuf' to 'struct _iobuf *'
        No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called
执行 cl.exe 时出错.

CommWizard.exe - 1 error(s), 0 warning(s)


敬请修改

我把程序嵌入后,有编译错误.
于是将代码改为:
FILE file;
file=fopen("c:\\test.txt","r");
if  ( file == NULL )
{
   //没有创建文件，则创建文件
    file=fopen("c:\test.txt","w");
   //写入数据
     file.write (strtemp);
   fclose(file);
}
else
{
    //表示创建了，则关闭后，在用追加方式写入
    fclose(file);
   file=fopen("c:\test.txt","a");
   //写入数据
    file.write (strtemp);
   fclose(file);
}

发现还有编译错误
错误如下:
--------------------Configuration: CommWizard - Win32 Debug--------------------
Compiling...
CommWizardDlg.cpp
E:\激光器驱动\温控电路相关资料\串口精灵源代码\CommWizardDlg.cpp(294) : error C2679: binary '=' : no operator defined which takes a right-hand operand of type 'struct _iobuf *' (or there is no acceptable conversion)
E:\激光器驱动\温控电路相关资料\串口精灵源代码\CommWizardDlg.cpp(295) : error C2678: binary '==' : no operator defined which takes a left-hand operand of type 'struct _iobuf' (or there is no acceptable conversion)
E:\激光器驱动\温控电路相关资料\串口精灵源代码\CommWizardDlg.cpp(298) : error C2679: binary '=' : no operator defined which takes a right-hand operand of type 'struct _iobuf *' (or there is no acceptable conversion)
E:\激光器驱动\温控电路相关资料\串口精灵源代码\CommWizardDlg.cpp(300) : error C2039: 'write' : is not a member of '_iobuf'
        d:\microsoft visual studio\vc98\include\mbstring.h(92) : see declaration of '_iobuf'
E:\激光器驱动\温控电路相关资料\串口精灵源代码\CommWizardDlg.cpp(301) : error C2664: 'fclose' : cannot convert parameter 1 from 'struct _iobuf' to 'struct _iobuf *'
        No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called
E:\激光器驱动\温控电路相关资料\串口精灵源代码\CommWizardDlg.cpp(306) : error C2664: 'fclose' : cannot convert parameter 1 from 'struct _iobuf' to 'struct _iobuf *'
        No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called
E:\激光器驱动\温控电路相关资料\串口精灵源代码\CommWizardDlg.cpp(307) : error C2679: binary '=' : no operator defined which takes a right-hand operand of type 'struct _iobuf *' (or there is no acceptable conversion)
E:\激光器驱动\温控电路相关资料\串口精灵源代码\CommWizardDlg.cpp(309) : error C2039: 'write' : is not a member of '_iobuf'
        d:\microsoft visual studio\vc98\include\mbstring.h(92) : see declaration of '_iobuf'
E:\激光器驱动\温控电路相关资料\串口精灵源代码\CommWizardDlg.cpp(310) : error C2664: 'fclose' : cannot convert parameter 1 from 'struct _iobuf' to 'struct _iobuf *'
        No user-defined-conversion operator available that can perform this conversion, or the operator cannot be called
执行 cl.exe 时出错.

CommWizard.exe - 1 error(s), 0 warning(s)


敬请修改

是你某个结构转换错误，与我写的那段关联不大