wtf different meaning

The margin tag can take one, two, three, and four parameters, each with a different meaning. margin:20px (upper, lower, left and right 20px.) ) margin:20px 40px; (upper, Lower 20px; left and right 40px.) ) margin:20px 40px 60px; (top 20px; left and right 40px; lower 60px.) ) margin:20px 40px 60px 80px; (upper 20px; right 40px; lower 60px; left 80px.) ）Using margin in CSS allows you to margin-top,margin-righ

types in GCC is 4 bytes. (1) What is the length of the int type ??...... Accurate bytes depend on machines and compilers ......Currently, 32bit (4-byte) PCs are generally 32bit in most compilers, and some compilers are also 16bit (such as Turbo C ). The most critical point is that it can only be small and cannot be big. This is because even if the compiler regards it as larger than 32 bits, but because the CPU length is only 32 bits, it can only process the number of 32 bits.At the same time,

before connection--max_allowed_packet=#//server receive/Send packet maximum length--net_buffer_length=#//tcp/ The IP and socket communication buffer size. --select_limit=#//Automatic restriction of the SELECT statement when using--safe-updates--max_join_size=#//automatic restriction of rows in joins when using--safe-updates--secure-auth// Refuse to connect to the database using (pre-4.1.1)--server-arg=name//send Embedded Server this as a parameter. --show-warnings//Display warningMySQL command-

As ruby is a pure object-oriented language, everything is an object. methods are objects and classes are objects ..., therefore, self has many environments. Only by distinguishing the meanings of self in different environments can we better understand the meaning of the program.I. Top Level ContextRuby codePuts selfPrint out main, which indicates the default Object main.2. In the definition of class or modu

And since Ruby is a completely pure object-oriented language, anything is an object, the method is an object, and the class is an object ..., so self has a lot of environments that distinguish the self meaning of different environments to better understand the meaning of the program. First level Ruby Code Puts self Print out Main, which represents the default obj