First look at the following section of code output what:#include int main () { int *p=null; printf ("%s", p); }Output , single-step debugging you can see that the value of executing int *p=null,p is 0x00000000, as you can see, NULL is 0 in
What is a null pointer constant (NULL pointer constant )?[6.3.2.3-3] an integer constant expression with the value 0, or such an expression cast to type void *, is called a null pointer constant.Here we will tell you: 0, 0l, '/0', 3-3, 0*17 (they
What is a null pointer constant (null pointer constant )?
[6.3.2.3-3] An integer constant expression with the value 0, or such an expression cast to type void *, is called a null pointer constant.
Here we will tell you: 0, 0L, '\ 0', 3-3, 0*17
Statement A pointer variable does not automatically allocate any memory. A null pointer is a pointer that does not point to anything. It can be assigned to a pointer to indicate that the pointer does not point to any position. The consequences of
What is a null pointer constant (null pointer constant)?
[6.3.2.3-3] An integer constant expression with the value 0, or such a expression cast to type void *, is called a null p OINTER constant.
This tells us: 0, 0L, ' yes ', 3-3, 0 * 17 (They are
NULL pointer Constants
An integer constant representing a value of 0, called a null pointer constant. For example: 0, 0L, 1-1 (both are integer constant expressions with a value of 0) and (void*) 0, void* null are NULL pointer constants, NULL
At some point, we need to assign the pointer to a null pointer to prevent the wild pointer. Some people prefer to use NULL as a null pointer constant, for example: int* p = NULL;. There is also a direct use of the 0 value as a null pointer constant,
C ++ File include rule constant definition
To sum up, C ++'s function declaration, variable declaration, and class definition are written in the header file, while function implementation, variable definition, and class method implementation are
In sqlserver 2000, the null value of datetime is the default value 00:00:00. in C #, the null value of datetime is the minimum value 0001-01-01 00:00:00. For database insertion, the date value updated to a null value is somewhat less than expected.
Class Definition details in C ++
Member variables
Each class can have no members or multiple members. The members can be data, functions, or type aliases.
A class can contain several public, private, and protected parts. Members defined in the
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