TAILIEUCHUNG - Validating Sequences

Mặc dù các ký tự trong chuỗi có thể thay đổi, họ vẫn phải tuân theo quy tắc nhất định định dạng. Trình tự xác nhận là thường tham gia nhiều hơn một chút so với các loại dữ liệu xác nhận chủ yếu bởi vì có rất nhiều điểm để kiểm tra xác nhận. | Validating Sequences A sequence is a string of characters letters numbers and special characters placed in a specific order or formatted in a special way. Following are some sample sequences Telephone number xxx-xxxx Credit card number xxxx xxxx xxxx xxxx Date xx xx xxxx URL http Although the characters within sequences may change they must still follow certain formatting rules. Sequence validation is typically a bit more involved than other types of data validation primarily because there are numerous validation points to check. By breaking down the process you can more readily understand how it works. The following are some validation points for a typical email address 1. It cannot contain more than one @ symbol. 2. It must include at least one period separating the actual domain name from the domain extension such as in or . 3. The last period must fall somewhere after the @ symbol but it can t be either of the last two characters. 4. The @ symbol cannot be the first or second character. 5. There must be at least two characters between the @ symbol and the first period that precedes it. 6. The email address must include at least eight characters aa@ . NOTE If an email address has been checked for the six points listed above you ve performed a reasonable validation. Although we could add many more validation points for example characters following the last period must be com net org or something similar your code would become extremely long and you would need to update it frequently to keep pace with changing Internet standards. It s crucial to determine the most important validation points and check for them. In this exercise we ll check only the following three validation points for text entered into the email_ti instance of our registration form The @ symbol must be included somewhere after the second character. The email address must include a period at least two characters after the @ symbol. The email address .

• Kỹ thuật lập trình
• máy tính
• mạng máy tính
• internet
• phần mềm
• ứng dụng
• lập trình
• SQL
• HTML
• sever
• web
• XML
• Phần cứng máy tính
• lắp ráp máy tính
• sửa chữa máy tính
• lỗi máy tính
• hệ thống mạch máy tính
• điện máy tính
• Tài liệu máy tính