如何查找特定字符串是否具有unicode字符（尤其是双字节字符）

To be more precise, I need to know whether (and if possible, how) I can find whether a given string has double byte characters or not. Basically, I need to open a pop-up to display a given text which can contain double byte characters, like Chinese or Japanese. In this case, we need to adjust the window size than it would be for English or ASCII. Anyone has a clue?To be more precise, I need to know whether (and