错误：粘贴"tmp_UINT"和"+"未提供有效的预处理令牌

Question

我有一个宏定义为：

#define GET_GENERIC_VAL(val_type, fmt_printf, prefix, suffix) 
val_type tmp_ ## val_type; 
rtc = (*(INOBJECT**)pObj)->getGeneric(meth, &(tmp_ ## val_type)); 
if (rtc == -1) { 
TRACE("Error: unable to get method for " #val_type " attribute " << attribute << " of object " << name); 
return -1; 
} 
sprintf(valueStr, fmt_printf, (prefix)(tmp_ ## val_type ## suffix));

并在开关大小写中调用此宏为：

switch (var_type) {
case 'u' : { GET_GENERIC_VAL(UINT      ,"%lu",UINT        , + 0        ); break; }
case 'i' : { GET_GENERIC_VAL(INT       ,"%ld",INT         , + 0        ); break; }
case 's' : { GET_GENERIC_VAL(STRING    ,"%s" ,const char *, + ''     ); break; }
case 'n' : { GET_GENERIC_VAL(NUMBER    ,"%s" ,const char *, .toString()); break; }
case 'b' : { GET_GENERIC_VAL(BYTESTRING,"%s" ,const char *, .toString()); break; }
case 'd' : { GET_GENERIC_VAL(DATE      ,"%s" ,const char *, .toString()); break; }
case 't' : { GET_GENERIC_VAL(TIME      ,"%s" ,const char *, .toString()); break; }
default : {
TRACE("Unknown type of attribute : type '" << var_type << "' for attribute '" << attribute << "' of object " << name << ".");
return -1;
}
}

我试图在 gcc 编译器上编译它，但编译器给出了以下错误：

error: pasting "tmp_UINT" and "+" does not give a valid preprocessing token         
error: pasting "tmp_INT" and "+" does not give a valid preprocessing token          
error: pasting "tmp_STRING" and "+" does not give a valid preprocessing token       
error: pasting "tmp_NUMBER" and "." does not give a valid preprocessing token       
error: pasting "tmp_BYTESTRING" and "." does not give a valid preprocessing token   
error: pasting "tmp_DATE" and "." does not give a valid preprocessing token         
error: pasting "tmp_TIME" and "." does not give a valid                             

任何人都可以帮助解决这个问题吗？ 在SUN平台上编译时，它工作正常。但是Linux的错误。

Answer 1

你的问题是错误的标记化：

sprintf(valueStr, fmt_printf, (prefix)(tmp_ ## val_type ## suffix));

从您使用宏的方式来看，您不想创建一个预处理器令牌，而是只想添加后缀。

试试这个：

sprintf(valueStr, fmt_printf, (prefix)(tmp_ ## val_type  suffix));