dtmf meaning

error, that is, it is also redirected to the file, the final result is that both the standard output and errors are redirected to the file.Command 2> 1> File2> 1 the standard error copies the standard output, but the standard output is still on the terminal.> The output is redirected to the file, but the standard error is still on the terminal. Use strace to see:1. Command> file 2> 1The key System Call Sequence for implementing redirection in this command is:Open (File) = 3Dup2 (3, 1)Dup2 (1

Linux Kernel and some other open-source code often encounter such code: do{ ...}while(0) Such code is not a loop at first glance. Do... while has no meaning at all on the surface, so why should we use it like this? In fact, do {...} while (0) is much more effective than beautifying your code. I checked some information and summarized the following advantages: 1. Help define complex macros to avoid errors when referencing: For example, s

testsequence print_any B1 Match with is really powerful, especially when the set is used as a branch. however, this is misleading, that is, the head above. Tail is not the header and bit in the linked list we understand. It is actually a placeholder symbol here. of course, this is because of the symbolic name, and the head and tail of the list are misleading: let listOfList = [[2; 3; 5]; [7; 11; 13]; [17; 19; 23; 29]] let rec concatList l = match l with | head :: tail -> he

Meaning of make mrproper and mrproper Before compiling a project in Linux, make mrproper is usually used to delete the files and configuration files generated before compilation and backup files. The differences between mrproper and distclean and clean are as follows, the makefile in the root directory of the Linux kernel source code has a clear explanation:Help:@ Echo 'cleaning targets :'@ Echo 'clean-remove most generated files but keep the config a

This article provides a detailed analysis of the differences between VC6X86 and VC9X86 in PHP and the meaning of NonThreadSafe. For more information, see PHP 5.3.0, however, there are several different versions available for download. That is, VC6 X86 and VC9 X86. First, let me answer: What is VC6?VC6 is compiled by the legacy Visual Studio 6 compiler. What is VC9?VC9 is the Visual Studio 2008 compiler, which is compiled by Microsoft VS editor.So

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 module:In the definition of class and module, sel

(Integer.tobinarystring (c));Output is 1001101001101100SummaryThis section describes the nature of char, which is fixed at two bytes, is actually an integer that represents the Unicode number of the character, the character not within the 65536 number is not represented by a char, and requires two char.Let's review all the previous chapters and sort out the ideas.We say that the so-called program, is mainly to tell the computer what data to do what the operation. In the 1th section we describe

Configuring the JDK environment variables1, new variable name: java_home, Variable value: C:\Program files\java\jdk1.7.0 (variable value is JDK installation path)2, open path, add variable value:%java_home%\bin;%java_home%\jre\bin ()3, new variable name: CLASSPATH, Variable value:.; %java_home%\lib\dt.jar;%java_home%\lib\tools.jar (note the first one.)Note:1,. Represents the current path,%java_home% is referring to the previously specified java_home;2,java_home indicates the JDK installation pat

, show myexception (I wrote) inherited from its parent class exception (System-written)This field is used to hold the "age illegal" string, but it is private in the parent class, and you can only assign it this way.Obviously the error message you gave was not thrown by the compiler at all. Specifically, to see the Java write source codeObviously only the private field in the parent class is assigned a value, and the exception class construct of a parameter you write makes sense.First we only loo

Ask the meaning of a wordpress statement $ templates = array (); If (''! ==$ Name) $ Templates [] = "header-{$ name}. php "; $ Templates [] = 'header. php '; This program judges whether $ name is null. if not, assign $ templates [] "header-{$ name}. php" But then $ templates [] = 'header. php'; then templates is finally header. php. What is the role of the previous judgment? Reply to discussion (solution) Consult th

In the smarty template file tpl, what is the meaning of "| h" next to the variable name when writing and outputting? smarty | h For example: " class="box60" style="; ime-mode: active;"> What is h after the variable in red? Reply to discussion (solution) | Pipeline (borrow operating system terms)Pass Template variables to functions Well, thank you. that is to say, "| h" is used in this way? Can you be specific? I'm a newbie, just now PHP. $ ArrF

In mysql, what is the meaning of: id and: id gt; $ orderid? $ Agentid = pdo_fetchcolumn ('select agentid from '. tablename ('shop _ order ').' Where id =: idLimit 1', array ( ': ID' => $ orderid )); In mysql, what does id =: id and ': ID' => $ orderid mean? : Is id a placeholder? $ Orderid is a parameter? Reply to discussion (solution) SQL command select agentid from '. tablename ('shop _ order'). 'where id =: id limit 1In: id

I-inject ---- invest L-loyal ---- loyal o-observant ---- heart V-Valiant ---- brave e-Enjoyment ---- Joy Y-Yes ---- willingness o-obligation ---- responsibility U-unison ---- harmony Therefore, love is investment, loyalty, care, courage, Joy, willingness, responsibility, and harmony. I haven't said it yet, but I did think about I lovey ou! Responsibilities! I-inject ---- Input Investment: There are many concepts involved in this investment. There are people you love and all your feelings, so th

When debugging CGI today, it is clear that the CGI program has been executed and the final result is correct, but the page is not refreshed. The test results in FireFox2.0 are normal, but IE6 is not refreshed! After careful investigation, we found that the cgi page is linked to Let's take a look at the meaning of void (0) in JavaScript: In JavaScript, void is an operator that specifies to calculate an expression but does not return a value.The form

When creating a database field and encountering a numeric type, such as int (4), I once thought it was a length. Later I tested it and found that no matter how many fields I set, the length of the inserted data is not affected. The related explanations are as follows: From: http://www.ccvita.com/175.htmlMeaning of X in MySQL int (X) This optional width specification is used to show the left fill of values whose width is shorter than the column width when the value is displayed, instead of limiti

Android self-learning course-callback function meaning (source code + example), android callback function Why do we learn the callback function? Let's start with the thread. Although I have written an article called "Android self-learning process-multithreading" before, I am still too young. When I was learning the thread, I tried to look at the Handler source code, so I became interested in the Callback interface. So I made up my own shortcomings and

Linux man command number meaning 1 User Commands 2 System call3 C Library Functions 4 Devices and Special Files 5 File Formats and Conventions 6 Games et. al. 7 Miscellanea 8 System Administration tools and Deamons www.2cto.com 1. commands that can be operated by users in the shell environment, executable files 2, and functions and tools that can be called by the System kernel, the functions provided by the kernel. For example, open, write (through th

The literal meaning of scale and aspect in the contentMode of UIView, uiviewcontentmode Scale means scaling. If it appears in contentMode, it is necessary to change the image size.Aspect means the aspect ratio. In contentMode, it means to keep the aspect ratio of the image and keep the image unchanged. Scale aspect fill: scale the image to make the image full of the container (fill) while maintaining the aspect ratio (aspect ).Scale aspect fit: sca

The meaning of function () {/* do something */}) (); is JavaScript. Run the anonymous function, and the variables in the anonymous function do not pollute the global variable space. Code: Execution result: Function 0 has no return value, runs, and does not pollute the space of the global variable I am running in a function anonymous. var inside undefined: falsevar inside values: inside function 1 returns a value, runs, and does not pollute

Meaning of time strings in NSDateFormatter, nsdateformatter A: AM/PM (morning/afternoon) A: 0 ~ 86399999 (the second microsecond Of A day) C/cc: 1 ~ 7 (the first day of the week, the day of the week is 1) Ccc: Sun/Mon/Tue/Wed/Thu/Fri/Sat (abbreviated as the day of the week) Cccc: Sunday/Monday/Tuesday/Wednesday/Thursday/Friday/Saturday) Dd: 1 ~ 31 (the day of the month, with 0) D: 1 ~ 366 (the day of the year, with 0) E: 1 ~ 7 (the day of the week, wi