.net中，怎么使用FILE

[oplm0082]

从vc6.0转成.net.有一部分文件读取的部分。
FILE *pStream;
pStream = fopen(fileName,"r+");
if ( pStream == NULL) {
AfxMessageBox( "Open file error!" );
return FALSE;
}
else{
CString strToRead;
fseek( pStream, 0L, SEEK_SET );
fscanf( pStream, "%s", strToRead );

}
fclose(pStream);
然后会提示内存读取错误，请问这是怎么回事，如何解决？？
ps:如果不调用fscanf语句，就不会出现错误。

[真相重于对错]

FILE *pStream= NULL <---------------
pStream = fopen(fileName,"r+");
if ( pStream == NULL) {
AfxMessageBox( "Open file error!" );
return FALSE;
}
else{
CString strToRead;
fseek( pStream, 0L, SEEK_SET );
fscanf( pStream, "%s", strToRead );

}
fclose(pStream);