Parameter . the character index is a zero - based index of text in the control , including spaces 此字符索引是控件中的文本（包括空格）的从零开始的索引。
This method enables you to determine the line number based on the character index specified in the 参数中指定的字符索引确定行号。控件中的第一行文本返回零值。
Method to search for text , you can obtain the character index to where the search results are found 方法搜索文本后，可以获得到找到搜索结果处的字符索引。可以用
No portion of the line wraps to the next , and the method returns 0 for the specified character index ，则该行不会换行到下一行，并且对于特定的字符索引该方法返回0 。
You can call this method with the character index returned by the find method to determine which line the word was found 方法返回的字符索引调用此方法以确定找到该单词的行。
If the character index specified in the index parameter is beyond the available number of lines contained within the control , the last line number is returned 参数中指定的字符索引超出控件中包含的可用行数，则返回最后一个行号。
Method returns the physical line number where the indexed character is located within the control . for example , if a portion of the first logical line of text in the control wraps to the next line , the 例如，如果控件中文本的第一逻辑行的一部分换行到下一行，则在指定的字符索引处的字符已经换行到第二物理行时，
