tailieunhanh - Using Variables

Sử dụng biến biến là một vị trí lưu trữ chứa một giá trị. Bạn có thể nghĩ của một biến như là một hộp giữ thông tin tạm thời. Bạn phải cung cấp cho mỗi biến trong một chương trình tên duy nhất. Bạn sử dụng tên của một biến để chỉ giá trị nó giữ. | Using Variables A variable is a storage location that holds a value. You can think of a variable as a box holding temporary information. You must give each variable in a program a unique name. You use a variable s name to refer to the value it holds. For example if you want to store the value of the cost of an item in a store you might create a variable simply called cost and store the item s cost in this variable. Later on if you refer to the cost variable the value retrieved will be the item s cost that you put there earlier. Naming Variables You should adopt a naming convention for variables that help you avoid confusion concerning the variables you have defined. The following list contains some general recommendations Don t use underscores. Don t create identifiers that differ only by case. For example do not create one variable named myVariable and another named MyVariable for use at the same time because it is too easy to get them confused. NOTE Using identifiers that differ only by case can limit the ability to reuse classes in applications developed using other languages that are not case sensitive such as Visual Basic. Start the name with a lowercase letter. In a multiword identifier start the second and each subsequent word with an uppercase letter. This is called camelCase notation. Don t use Hungarian notation. Microsoft Visual C developers reading this book are probably familiar with Hungarian notation. If you don t know what Hungarian notation is don t worry about it IMPORTANT You should treat the first two recommendations as compulsory because they relate to Common Language Specification CLS compliance. If you want to write programs that can interoperate with other languages such as Microsoft Visual Basic .NET you need to comply with these recommendations. For example score footballTeam _score and FootballTeam are all valid variable names but only the first two are recommended. Declaring Variables Remember that variables are like boxes in memory that