Complex if-statement in an textchanged event
问题 I want to realize a complex if-statement. The if-statement is in an textchanged event of a textbox. If the if-statement gives true, a pdf-file should be load. The problem is not how to load the PDF-file, thats works already fine, the problem is, how set the if-statement. There, the following conditions should be queried: At position 0 must be an "S", at position 1 must be an "E", at position 2 must be an "H", position 3 does not matter, position 4-7 represent a number and the number must be