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These mistakes are usually the result of confusion between Null and either 0 (zero) or an empty string (a string value with a length of zero, represented in SQL as ''). Null is defined by the SQL standard as different from both an empty string and the numerical value 0, however. While Null indicates the absence of any value, the empty string ...
By returning a null object (i.e., an empty list) instead, there is no need to verify that the return value is in fact a list. The calling function may simply iterate the list as normal, effectively doing nothing. It is, however, still possible to check whether the return value is a null object (an empty list) and react differently if desired.
In C, two null pointers of any type are guaranteed to compare equal. [3] Prior to C23, the preprocessor macro NULL was provided, defined as an implementation-defined null pointer constant in <stdlib.h>, [4] which in C99 can be portably expressed as ((void *)0), the integer value 0 converted to the type void* (see pointer to void type). [5]
In C, variables with static storage duration that are not initialized explicitly are initialized to zero (or null, for pointers). [ 3 ] Not only are uninitialized variables a frequent cause of bugs, but this kind of bug is particularly serious because it may not be reproducible: for instance, a variable may remain uninitialized only in some ...
In all modern character sets, the null character has a code point value of zero. In most encodings, this is translated to a single code unit with a zero value. For instance, in UTF-8 it is a single zero byte. However, in Modified UTF-8 the null character is encoded as two bytes : 0xC0,0x80. This allows the byte with the value of zero, which is ...
The BIT data type, which can only store integers 0 and 1 apart from NULL, is commonly used as a workaround to store Boolean values, but workarounds need to be used such as UPDATE t SET flag = IIF (col IS NOT NULL, 1, 0) WHERE flag = 0 to convert between the integer and Boolean expression.
Null (SQL) (or NULL), a special marker and keyword in SQL indicating that something has no value; Null character, the zero-valued ASCII character, also designated by NUL, often used as a terminator, separator or filler. This symbol has no visual representation. Null device, a virtual file that discards data written to it, on Unix systems /dev/null
The null coalescing operator is a binary operator that is part of the syntax for a basic conditional expression in several programming languages, such as (in alphabetical order): C# [1] since version 2.0, [2] Dart [3] since version 1.12.0, [4] PHP since version 7.0.0, [5] Perl since version 5.10 as logical defined-or, [6] PowerShell since 7.0.0, [7] and Swift [8] as nil-coalescing operator.