correct value Undefined variable Undefined, a function or variable lacking a declaration Undefined, a variable lacking initialization Undefined, an unavailable...

An undefined variable in the source code of a computer program is a variable that is accessed in the code but has not been declared by that code. In some...

In computer programming, a program exhibits undefined behavior (UB) when it contains, or is executing code for which its programming language specification...

(identifier's) meaning. Declarations are most commonly used for functions, variables, constants, and classes, but can also be used for other entities such...

often has an undefined, arbitrary value if accessed (see wild pointer), since it has yet to be explicitly given a particular value. A variable whose extent...

the special \nnn octal notation supported, see %$CLS%. While the variable is undefined by default under DOS Plus and DR-DOS, the Multiuser DOS default...

required every time an undefined value is dereferenced. Perl autovivification allows a programmer to refer to a structured variable, and arbitrary sub-elements...

prevent more serious problems. For example, when encountering an undefined variable, MUMPS generates an error where MIIS treats it as nil. In the 1980s...

usually treat undefined values explicitly when possible. For instance, Perl has undef operator which can "assign" such value to a variable. In other type...

which is known as variable hoisting. Behavior of names in context that have undefined value differs: in Python use of undefined names yields a runtime...

Lovelace defines a hitherto undefined variable ( V 13 {\displaystyle V_{13}} ) by itself, thereby assuming that all undefined variables are automatically equal...

is reported to the user as an undefined variable. This has the pleasant side effect of checking for undefined variables with essentially no CPU overhead...

values at the last exit, while the values of declared variables that are not marked with own is undefined. — Revised report on ALGOL 60, section "5. Declarations"...

first line were omitted, the program would trigger an error on the undefined variable p during compilation. However, the program would still be syntactically...

configured, then an undefined variable evaluates to its name, in upper case. The built-in function SYMBOL returns "VAR" for a defined variable and does not trigger...

automatic variables.) All variables declared within a block of code are automatic by default. An uninitialized automatic variable has an undefined value until...

is undefined. The answer that it must be 10 assumes that it started at zero, which may or may not be true. Note that in the example, the variable i is...

and HTML elements in the Document Object Model (DOM). When an undefined JavaScript variable is declared in the same context as an HTML element with the...

random variables, one can show that both E[X +] = ∞ and E[X −] = ∞ (see Harmonic series). Hence, in this case the expectation of X is undefined. Similarly...

results are not trustworthy. Using aqueous electrodes introduces undefined, variable, and unmeasurable junction potentials to the cell in the form of...

expectation of a circularly symmetric complex random variable can only be either zero or undefined. Additionally, E ⁡ [ Z Z ] = E ⁡ [ e i ϕ Z e i ϕ Z ]...

Incomplete opcode decoding Logic redundancy Undefined behaviour Undefined variable Uninitialized variable Four-valued logic Nine-valued logic Examples...

"mathematical backbone" for dealing with problems where variables change with time or another reference variable. Infinitesimal calculus was formulated separately...

any statistical relationship, whether causal or not, between two random variables or bivariate data. Although in the broadest sense, "correlation" may indicate...

Bihar. Falling Rain Genomics. Retrieved 10 March 2009. " Notice: Undefined variable: Post in /Opt/Lampp/Htdocs/Zhouyong/Icas.co.in/List.PHP on line 29"...

Cauchy distribution. The distributions have undefined variance for α < 2 {\displaystyle \alpha <2} , and undefined mean for α ≤ 1 {\displaystyle \alpha \leq...

Curly braces syntax: $f = "sqrt"; $x = 25; echo "a$xc\n"; // Warning: Undefined variable $xc echo "a{$x}c\n"; // prints a25c echo "a${x}c\n"; // also prints...

would be undefined (because the multiplications 0 ⋅ ∞ {\displaystyle 0\cdot \infty } and 0 ⋅ ( − ∞ ) {\displaystyle 0\cdot (-\infty )} are undefined). The...

forward reference is not possible. With var a variable's value is undefined until it is initialized. Variables declared with let or const cannot be accessed...

programming, values held in program variables whose content never changes are known as constants to differentiate them from variables that could be altered during...