NSArrayand NSMutableArray --arrays are ordered sets of multiple objects. Accesses an object by specifying its location (that is, the index) in the array. The index of the first element in the array is 0 (0).
NSDictionaryand NSMutableDictionary --the dictionary stores its entries as key-value pairs; The key is a unique identifier, usually a string, and the value is the object you want to store. You can access the object by specifying the key.
NSSetand NSMutableSet --the collection stores a
What is a function?A function is a method or a program that can implement certain functions, and a simple understanding of the concept of a function is that you write statements that, for ease of use, combine these statements to give it a name, the function name. When you use this name, you can implement the function in the statement group.Some of the functions in Python are called built-in functions and do not need to be written by ourselves. There is also a third-party function, is the other p
= true; # define the continue handler for not
Found flag
Set fetchSeqOk = false;
Open fetchSeqCursor;
FetchSeqLoop: Loop
If fetchSeqOk then
Leave fetchSeqLoop;
Else
Fetch cursor into _ seqname, _ value;
Select _ seqname, _ value;
End if;
End Loop;
Close fetchSeqCursor;
This is a complete process, so people who will think about it will generally think about it here. if so, how to implement nested cursor loop failover, here, we can implement commit based on the scope of the statement block. Mys
10.1.5 Refactoring Members There is a handy technique for adding properties, you can generate properties from fields there is a handy technique for adding properties, you can generate a genus from a field, and here is an example of refactoring (refactoring), which means modifying the code using tools rather than manually modifying it . To do this, just right-click a member in the class diagram, or right-click a member in Code view.For example, if the MyClass class contains the following fields:
In shell, what are the special definitions of numbers? -- Linux general technology-Linux programming and kernel information. The following is a detailed description. LOG_DIR =/var/log
ROOT_UID = 0 # $ when the UID is 0, the user has the root user permission.
LINES = 50 # default number of LINES saved
E_XCD = 66 # Cannot modify the directory?
E_NOTROOT = 67 # non-root users will exit with an error
If ["$ UID"-ne "$ ROOT_UID"]
In t
through: unset array [subscript] can clear the corresponding element, without subscript, clear the entire data.
3. Special use
Sharding:
A= (1 2 3 4 5)Echo ${a[@]:0:3}1 2 3Echo ${a[@]:1:4}2 3 4 5
C= (${a[@]:1:4})echo ${#c [@]}4Echo ${c[*]}2 3 4 5
Directly through the ${array name [@ or *]: Start position: Length} Slice the original array, return is a string, the middle with "space" separate, so if you add "()", will get the slice array,
name[20]; /* Student Name */char sex; /* Gender */Long num; /* Study Number */float score[3]; /* Three subjects test results */} Person1,person2; /* Define the struct type variable */The definition method cannot be used to define the struct type variable, except for the direct definition, because the struct type cannot be recorded. 4) Define a struct type in C to use a typedef:typedef struct STUDENT{int A;}stu;So when declaring variables, you can: Stu stu1;If there is no typedef, a struct Stude
) { - varstr = params.query.callback + ' (' + json.stringify (reqdata) + ') ';//Jsonp - res.end (str); -}Else{ + res.end (Json.stringify (Reqdata)); - } +});We need to determine the property name "callback"--if (Params.query params.query.callback) {} for the callback function that has a contract after obtaining the parameter. If not I think I can do the normal get (Ajax) to deal with, instead I think it is JSONP. Jsonp needs to return the result in a "call" way:Params.query.callback
Mysql and oracle table field definitions comparison description mysql oracle VARCHAR www.2cto.com variable-length string VARCHAR [0-65535] definition length is calculated by default, if it is GBK-Encoded chinese characters will occupy 2 bytes, if the total byte length of the field definition exceeds 65535, it will be automatically converted to the MEDIUMTEXT type definition VARCHAR2 [1-4000] VARCHAR is a synonym definition of VARCHAR2. By default, tin
Enumerations are the basic data types that programmers define themselves, and variables of this type can only take the values in the enumeration, and the benefit is the ability to prevent the erroneous assignment of variables. Usage: Enum type name {variable 1, variable 2, variable 3, ...}C language macro definition is defined in the program head, for preprocessing, there are no parameters and two, can be regarded as a process of invocation, and function calls are not the same, not involved in t
of the "# #" Connection symbol, "# #" function is to connect token, the above example, format. Args,__va_args can be seen as tokens. Assuming that token is empty, "# #" is not connected. So agree to omit the variable number of parameters.Retrofit of the above 2 demo examples:#define LOG (format, ...) fprintf (stdout, format, # #__VA_ARGS__) #define LOG (format, ARGS ...) fprintf (stdout, format, # # ArgsIf the number of parameters can be omitted, then a macro is used to define a switch. The fun
As we all know, multi-line text box textarea can not be arbitrarily adjusted, such as, if you want to adjust, you have to write a lot of script:This is good, because in many cases, we do not need to open to the user to adjust the text box, often just need to set the Col and row properties, fixed its size can be.However, Google Chrome, for, an ordinary:But it can be easily adjusted as follows:This will drag our page layout, and sometimes debugging do not know how to do, and thought the style is n
virtual functionSometimes a virtual function in a base class is defined for use in a derived class, and it has no meaning in the base class. Such functions are called pure virtual functions, which do not need to be written in the form of empty functions, but simply declared as:virtual function type function name (formal parameter table column) =0;Note: There is no function body for pure virtual function;The Last "= 0" does not mean that the return value of the function is 0, only the formal fun
There are three ways to define JS objectsThere are three ways of defining JS methodsfunction fn () {}var fun = function () {}var fun = new function () {}//******** *********************************////var a = "123"; //function fn () { //alert (a); //var ab = "4321"; // } //fn (); //new Object (); //create a normal object varA = 3, B = 9; varobj = { //Defining PropertiesName: "123", Fun1:function () { } }
MySQL adds, modifies, and deletes TABLE columns and constraints. TABLE definitions such as bitsCN. comALTER TABLE: adds, modifies, and deletes TABLE columns and constraints.
View column: desc table name;
Alter table t_book rename to bbb;
Add column: alter table name add column name varchar (30 );
Delete column: alter table name drop column name;
Alter column name MySQL: alter table bbb change nnnnn hh int;
Modify the column name SQLServer: exec sp_re
PHP arrays are much more powerful than arrays of other languages, let's look at the basic concepts of arrays and how they are defined:
The above is the Android programmer to learn PHP development (19)-Array (1) Basic concepts and definitions of-phpstorm content, more relevant content please pay attention to topic.alibabacloud.com (www.php.cn)!
Sometimes, we need to make the code simple so that it's easy to read code. We can extract some unchanging stuff and change things as parameters. Defined as a macro, so it's much easier to write.The following examples illustrate some common macro definitions and share them with you:1. Determine if the device's operating system is IOS7#define IOS7 ([[[ uidevice currentdevice].systemversion Doublevalue] >= 7.0])2. Determine if the current device is IPho
actually interpreted, and there is a semicolon at the end of the function expression, just like declaring other variables. The third method is generally not recommended, because this syntax can result in parsing two of times of code (parsing the regular ECMAScript code for the first time, and the second parsing the string passed into the constructor), thus affecting performance.result:5Retult:5Note: Because the function name is just a pointer to a function, a function may have more than one nam
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