C ++ type (1), Type

C ++ type (1), Type

Variable

Functions of Variables

• Where is the information stored?
• Value to store
• Storage type information

Naming rules

• Only letters, numbers, and underscores can be used in the name.
• The first character of the name cannot be a number.
• Case Sensitive characters
• The C ++ keyword cannot be used as a name.
• Names starting with two underscores (_) or underscores (_) and uppercase letters are reserved for the compiler and its resources. names starting with an underscore are used as global identifiers.
• The length of the C ++ name is unlimited.

Integer

1 int _tmain(int argc, _TCHAR* argv[])2 {3     using namespace std;4     cout << sizeof(short) << endl;5     cout << sizeof(int) << endl;6     cout << sizeof(long) << endl;7     cout << sizeof(long long) << endl;8     return 0;9 }

Integer literal

Decimal, octal, hexadecimal, and other representation methods are only used to facilitate expression. They are all stored in binary format.

The following are the cout output methods,

1 int waist = 42; 2 cout <waist <endl; 3 cout 

Const qualifier

The common format for creating constants is as follows:

Const type name = value; const must be initialized in the Declaration.

Const comparison # advantages of define:

• Can explicitly specify the type
• You can use the scope rules of C ++ to restrict the definition to a specific function or file.
• Const can be used for complex types.

Floating Point Number

Floating point numbers can be divided into three types: float, double, and long double. These types are described based on the valid digits they can represent and the minimum allowable exponential range. For example, 2.5, 3.32e + 022, and 1.23f are all floating point numbers.

Advantages and disadvantages of floating point over INTEGER:

• It can be a value between integers.
• The value range is greater than the integer value.
• The operation speed is slower than the integer and the accuracy is low.

Type conversion

• Convert the initialization value

C ++ allows the value of one type of variable to another type of variable. This type of conversion usually results in loss of data accuracy.

1     int num1 = 5;2     float num2 = num1;

• Conversion during initialization in {} mode

This conversion method requires strict requirements. The list initialization does not allow narrowing. For example, you cannot convert a floating point to an integer.

• Convert in Expression
• Transfer Parameters

Similar to the first conversion method

• Forced type conversion

The general format is as follows:

Method C: (typename) value

C ++ method: typename (value) static_cast <typename> (value)

1     char ch = 'A';2     cout << static_cast<int>(ch) << endl;