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What are the difference between null and undefined in Javascript?
Wiki User
∙ 7y ago
EMPTY STRING-it is a unique string of length zero.the empty string is still a sring upon which strin operation may be attempted.
NULL STRING-In programming ,a character string that contais no data.
Wiki User
∙ 14y ago
Wiki User
∙ 7y agoundefined means a variable has been declared but has not yet been assigned a value. On the other hand, null is an assignment value. It can be assigned to a variable as a representation of no value. Also, undefined and nullare two distinct types: undefined is a type itself (undefined) while null is an object
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What is the difference between null pointer ASCII null character and null string?
A null pointer is a pointer which does not point to any valid memory location, and usually contains the binary value "0" to represent this (this is language dependent). The ASCII null character is a character-sized zero value (in ASCII, it is an unsigned byte with a value of 0), and typically represents the end of a string (esp. as in C and C++). A null string is one that is zero characters of usable string data; in a length-based string, this means the length parameter is set to 0, and in an ASCII null-terminated string, means the first character is set to 0.
If null is compared with null what is the result-true or false or null or unknown?
You mean SQL? NULL = anything IS NULL NULL <> anything IS NULL ... NULL IS NULL = TRUE NULL IS NOT NULL = FALSE
What is the difference between an array shift and unsetting a variable in PHP?
By shifting the values in an array, you are moving a key's value to the previous key. The very first key's value is obliterated. By shifting all values in the array, all keys will have a value of NULL. Unsetting a variable is entirely different -- performing a variable unsetting causes the variable to have a value of NULL, as if it was never set.
What is the difference between a null pointer and a null macro?
Using a NULL macro to make C portableI'll assume that you're asking your question for C type language programming. A NULL pointer is a pointer that's guarnteed to point to nothing. This may be 0 in a UNIX/Linux system or some other address in another system. Using the NULL macro to set/initialize your pointers will make your programs more portable among systems than using something like the 0.#include char *c = 0; // initialize to NULL--not portablechar *p = NULL; // initialize to NULL as defined in stdio is portableAddendumThe code:char *c = 0;actually is portable because the compiler converts 0's used in a pointer context (cast to a pointer) to the machine's representation of a NULL pointer, which may or may not be all 0 bits. The NULL macro itself might be defined as something like 0 or (void *)0, and both definitions are portable. As a corollary, the following code is also portable:if (!c) {// do something}because it is equivalent to:if (c != 0) {// do something}and the 0 above is converted to a NULL pointer because it is being compared with a pointer.
C plus plus program of periodic table?
The Periodic Table Of Elements has a well defined order. The layout can be emulated easily since the arrangement is quite logical.The first step would be to define a struct containing the following members as a minimum:- atomic number (int - number of protons in its nucleus)- symbol (char* - short form of the element name)- name (char* - long form of the element name)i.e.:struct elementinfo {int atomicnumber;char *symbol, *name;};Other members can be added as your program develops.The next step is to arrange the table itself. If you're using Win32 or another graphical system, it's a matter of drawing a box (Win32 would require a MoveToEx() call and four LineTo() calls) and TextOut() (or a related function) for the atomic number and element symbol (centered horizontally and aligned top and bottom respectively).Including conio.h or curses.h would give you the ability to position the cursor and even change the text color, allowing for an alternate "graphical" method.To keep things simple, storing the elements in an array would require something akin to the following:struct elementinfo elementlist[]={{1, "H", "Helium"}, {0, NULL, NULL}, {0, NULL, NULL},{0, NULL, NULL}, {0, NULL, NULL}, {0, NULL, NULL},{0, NULL, NULL}, {0, NULL, NULL}, {0, NULL, NULL},{0, NULL, NULL}, {0, NULL, NULL}, {0, NULL, NULL},{0, NULL, NULL}, {0, NULL, NULL}, {0, NULL, NULL},{0, NULL, NULL}, {0, NULL, NULL}, {2, "He", "Helium"},{-1, NULL, NULL},{3, "Li", "Lithium"}, {4, "Be", "Beryllium"}, {0, NULL, NULL},{0, NULL, NULL}, {0, NULL, NULL}, {0, NULL, NULL},{0, NULL, NULL}, {0, NULL, NULL}, {0, NULL, NULL},{0, NULL, NULL}, {0, NULL, NULL}, {0, NULL, NULL},{5, "B", "Boron"}, {6, "C", "Carbon"}, {7, "N", "Nitrogen"},{8, "O", "Oxygen"}, {9, "F", "Fluorine"}, {10, "Ne", "Neon"},{-1, NULL, NULL},...{-2, NULL, NULL}};In the above array, {0, NULL, NULL} represents a blank displayed for that particular cell, and {-1, NULL, NULL} represents a newline. The {-2, NULL, NULL} signifies the end of the table. The following for() loop would wrap around your display code like so:for (count=0; elementlist[count].atomicnumber!=-2; count++) {if elementlist[count].atomicnumber==-1) {// jump to next line of elements}else {// display current element}}Drawing this graphically, you'd have to keep track of the current cursor (X, Y) position.If you are sending this to stdout or another text stream (i.e. text file), you could draw each line, referencing the array of elements as you go. The list of elements would have to be stored in a nested array: the outermost array contains each line of elements in an array. This would do away with the {-1, NULL, NULL} terminating each line of elements.Extending this code to use classes would be relatively simple, but might only make sense if you were drawing this graphically storing each element as an object.The Lanthanides and Actinides, since they're displayed separately from the main table, would probably have to be stored separately for sake of convenience.Also, as laboratories continue to synthesize (or, on the rare chance, discover) new elements, the layout of the table may change (even drastically) to suit. Thus, the code would have to be altered accordingly.See the related links below for more ideas on how to design a program that displays the Periodic Table of Elements.(Note: Code originally posted was copyrighted. Added to related links.)
What is the difference between equals 0 and equals NULL?
NULL is for pointers, 0, for numbers
What is the difference between 0 and null?
Nothing - 0, Zero and null are the same things
What is difference between null value and not null value?
Putting it very simply a null value is empty and a not null value contains something.
What is the difference between zero vector and null vector?
They are the same.
What is the difference between a null hypothesis and a research hypothesis?
The null hypothesis is the default hypothesis. It is the hypothesis that there is no difference between the control group and the treatment group. The research hypothesis proposes that there is a significant difference between the control group and the treatment group.
What is the difference between array and string of array?
When we declare an array of characters it has to be terminated by the NULL , but termination by NULL in case of string is automatic.
What is the difference between two source hypothesis and two gospel hypothesis?
null
What is the major difference between the null and alternative hypothesis?
In research, a null hypothesis means that no results will be found. An alternative hypothesis means that results will be found.
What is the difference between alternative hypothesis and null hypothesis?
In research, a null hypothesis means that no results will be found. An alternative hypothesis means that results will be found.
What happens when null pointer is released?
Undefined behavior. Literally anything can happen. ------------------------------------------------------------------ And does with one exception that I know of, DJGPP (for DOS). Obviously before freeing a pointer it is tested for being NULL.
In testing for differences between the means of two related populations the null hypothesis is?
That there is no difference between the means for the two populations.
What hypothesis states that there is no change no difference or no new finding?
null
