sexy prone

Error-prone knowledge points in C Language1. Structure Calculation // Struct BBB {// long a; // char c1; // char c2; // long B; // long c; //} * p; // sizeof (struct BBB) = 16; // int main () // {// p = (struct BBB *) 0x100000; // printf ("0x % x", p + 0x1); // Add the entire struct size to 0x10010 // printf ("0x % x ", (unsigned long) p + 0x1); // integer plus 1, 0x100001 // printf ("0x % x", (unsigned long *) p + 0x1 ); // Add sizeof (unsigned long)

Oracle is prone to errors. logical comparison of null and ''1. In Varchar2 format,'' is equivalent to null (no memory is allocated ). [SQL] the result of the statement 'aa from dual where ''is null exists in select.2. logical judgment on null is not allowed in Oracle, and only is and is not can be used. [SQL] select 'has 'aa from dual where null = null; [SQL] select' has 'aa from dual where null

>b?a:b>c? (A>B?A:B): C13. There are the following proceduresMain (){Char s[]= "ABCD", *p;for (p=s+l; p {printf ("%s", p);}}The output of the program is: (D)A. ABCD BCD CD D B. A B c D c. B C D d. BCD CD D14. The address of a variable is called a pointer to the variable (√)15. Recursive invocation of a function is simply a function that invokes itself directly or indirectly. (√).Any expression statement is composed of an expression plus a semicolon. (√)17. There is the following procedure main ()

!"); } In this case, there are benevolent see, but there are cases where the brackets will behave differently. This is because the semicolon insertion mechanism (semicolon insertion mechanism)--javascript is not picky, and when you choose not to end a line of code with a semicolon, JavaScript will help you fill it yourself. This behavior can cause trouble, such as when you return an object literal, while the opening parenthesis is on the next line: Warning: Unexpected return va

usually introduced externally.5. When executing the code, CSS takes the form of asynchronous parsing of HTML code while parsing the CSS code while performingJS using synchronous mode, when the resolution encountered JS code or JS introduced, will be the full load of JS code parsing will be parsed after the HTML and CSS code.6. and | | Small differences from other languages1 2, first execute 1, if 1 is false, then return false directly, no longer see 2;If 1 is true, then look at 2 and finally r

program.5.SCANF () seriesscanf () sscanf () fscanf () vfscanf () vscanf () vsscanf ()The functions of the SCANF series are also poorly designed. In this case, the destination buffer will overflow. Consider the following code: void Main (int argc, char **argv) { Char buf[256]; SSCANF (Argv[0], "%s", buf); } If the input word is greater than the size of the BUF, there is an overflow condition.There are several other situations:A) The use of "%x" or "%d", but the last

unit as a scaling factor to uniformly control the row height, and the scaling factor is inherited directly rather than inheriting the computed value. (Quoted from http://www.ddcat.net/blog/?p=227)Vertical-align applies to inline element and cell (Table-cell) element attribute values:The top alignment (vertical-align:top) aligns the top of the inline box of an element with the top of the row box.The text top alignment (vertical-align:text-top) aligns the top line of the text line with the top of

Summarized some common pointer error-prone issues (2), pointer FAQs 4. pointers and Arrays Some common mistakes are that arrays and pointers are completely interchangeable. Although the array name can be used as a pointer sometimes, the array name is not a pointer. An array is a continuous set of homogeneous elements that can be accessed using indexes. (Continuous means that the element of the exponential group is adjacent in the memory, and there is

initialization y y=new y () so call Y's construction method to print Y4. Constructor initialization for subclasses: Execute code in construction method print ZThe result is: yxyzDebug mode:Case:Package Cn.itcast.extend;public class Demo {public static void main (string[] args) {Zi z=new Zi (); Z.show ();}} Class Fu{int num=10;public void Show () {System.out.println (num);}} Class Zi extends Fu{int num=20;public void Show () {System.out.println (num);}}The result is no doubt:Remove the Show meth

alignment: 4 6 84-byte Alignment: 6 8 123. If there is no break in the case statement, then the statement after it will be executed.4. Pointers and const declarations:(1) The object referred to by the pointer is readableconst int *p;int const *P;(2) The pointer is readableint *const p;(3) Pointers and pointers refer to objects that are readableconst int * const P;int const *CONSTP;5. Dynamic opening upvoid GetMemory (char *p,int len) {p= (char *) malloc (len);} int main () {char *p;GetMemory (p

that the timer still does not trigger the event. What is this for?This is because when the timer is added, we need to specify a mode, because the runloop of the same thread can only be in one mode at any time when it is running. So only when the program is in this mode can the timer get the chance to trigger the event.To cite an inappropriate example, we say that the brothers are representative of the runloop of the Mode,timer on behalf of their own bucket, and then a group of people to the lin

installation ruby2.3.0, start reading the download progress, the file only about 12 trillion, but the download speed extremely easy to fail , I tried 5, 6 times to fix, need patienceThe success will be a bunch of hints: if you see a line that is the Install of ruby-2.3.0-#complete ; The new Ruby version is ready.$RVM use 2.3.0 //ruby can co-exist in multiple versions, and after downloading, you can $ruby-V with commands, and check the current Ruby version3. Start the installation again Cocoapod

Today in writing a Uibarbuttonitem classification, when Xcode automatically prompt, because not careful review, the wrong will need to use the SetBackgroundImage place, select into SetImage, resulting in the button's bounds setting is unsuccessful, Navigating the item doesn't show up. Later looked for a long time finally found the cause of the problem, depressed Ah! Really near misses great difference Ah, next time must look carefully! Mark here to avoid the subsequent repetition![BS-08] Note Xc

PHP programmers are prone to 10 errors. PHP is a great web development language and flexible language, but we can see some mistakes made by php programmers. I made the following list and listed 10 PHP programmers who often commit crimes. PHP is a great web development language and flexible language, but I can see some errors that php programmers make repeatedly. I made the following list to list the 10 errors that PHP programmers often make, most of w

Which of the following empty functions is php easy to use? In the official php manual, I wrote ,? Check whether a variable is empty. If var is a non-null or non-zero value, empty () returns FALSE. In other words, "", 0, "0", NULL, FALSE, array (), var $ var, and empty functions that are not prone to php errors ? According to the official php Manual, ?Check whether a variable is empty. If var is a non-null or non-zero value, empty () returns FALSE. I

The following are nine traps that JavaScript is prone to mistakes. Although it is not a very profound technical problem, it makes programming easier, that is, make life easier.1. last comma For example, in this Code Section, note that the last comma should be good in terms of Linguistics (this is acceptable for a dictionary similar to the data type in Python ). Internet Explorer reports syntax errors, but it is not detailed. You can only scan thousand

Today, I found an interesting piece of code while reading the code. #include First, let's guess what the execution result of this code is? It looks very simple. Many people say the results are as follows: Child PID [% d]Parents PID [% d] The result is as follows: Child PID [% d] Child PID [% d] If the code is changed to If (pid = fork () The results are as expected: Child PID [% d]Parents PID [% d] The reason is the operator priority. Because the priority of the o

Practical English: 30 sentences which are the most prone to mistakes in Chinese 1. I very like it I like it very much.2. This price is suitable for me.The price is very suitable for me. The price is right.Note: The most common use of suitable is to appear in notices or notices in the form of negation. For example, it is not suitable for children in the following programs. The following programme is not suitable for children is more appropriate to use

the battery. Avoid using laptops in High Temperature environments or at high loads, in case of automatic power failure, you can take out the battery and place it in a shaded place for a moment and then restart the system. In addition, when the performance of the battery is greatly reduced, it can be fully charged and discharged several times, but note that the battery correction should not be too frequent, otherwise it will affect the life of the battery. Note: Battery is a consumable part. If

In HTML, the percentage width and position of the box after relative, absolute, and fixed are prone to errors. 1. relative Positioning relative: as the name suggests, relative positioning is offset relative to its own position, for example: Take the center of the box as the benchmark, which is the positive direction of each edge, for example: Move 20px to the right: the code is left: 20px; or right:-20px; Move 20px down: the code is top: 20px; o