Mastering c pointers

To be master in pointers you must know how to read any types of pointers in c.

Rule 1: Determine the priority of pointer declarations by taking into account both precedence and associativity according to following table.

1. Where
2. 1. (): Functions as the bracket or function operator.
3. 2. []: Serves as the array subscription operator.
4. 3. *: Acts as the pointer operator, not to be confused with the multiplication operator.
5. 4. Identifier: Not an operator, but the name of a pointer variable. The highest priority is always assigned to the name of the pointer.
6. 5. Data type: Not an operator either. Data types include modifiers (e.g., signed int, long double, etc.).

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You will understand it better by examples:

(1) How to read following pointer?

char (* ptr)[3]

Answer:

Step 1: Both () and [] operators share equal precedence. Consequently, the priority is determined by the rule of associativity. As their associativity is left to right, the first priority is assigned to ().

Step 2: Within the brackets, both * and ptr operators have equal precedence. Following the rule of associativity (right to left), the first priority is assigned to ptr, while the second priority goes to *.

Step 3: Allocate the third priority to the [] operator.

Step 4: As data types have the least priority, assign the fourth priority to "char".

Now read it following manner:

ptr" is a pointer to a one-dimensional array of size three, containing data of type "char.

(2) How to read following pointer?

float (* ptr)(int)

Answer:

Assign the priority considering precedence and associative.

Now read it following manner:

"ptr" is a pointer to a function that takes an integer-type parameter and returns a float-type value.

Rule 2: Determine the priority of each function parameter individually and read each parameter separately.

Understand it through following example.

(3) How to read following pointer?

void (*ptr)(int (*)[2],int (*) void))

Answer:

Assign the priority considering rule of precedence and associative.

Now read it following manner:

"ptr" is a pointer to a function with two parameters. The first parameter is a pointer to a one-dimensional array of size two containing data of type int. The second parameter is a pointer to a function that takes no parameters (void) and returns a value of type int. The return type of the main function is void.

(4) How to read following pointer?

int ( * ( * ptr ) [ 5 ] ) ( )

Answer:

Assign the priority considering rule of precedence and associative.

Now read it following manner:

"ptr" is a pointer to an array of size five, where each element is a pointer to a function that takes no parameters (void) and returns a value of type int.

(5) How to read following pointer?

double*(*(*ptr)(int))(double **,char c)

Answer:

Assign the priority considering rule of precedence and associative.

Now read it following manner:

"ptr" is a pointer to a function that takes an integer-type parameter and returns a pointer to another function. The latter function has two parameters: the first one is a pointer to a pointer of double data type, and the second one is of char type. The return type of the inner function is a pointer to double data type.

(6) How to read following pointer?

unsigned **(*(*ptr)[8](char const *, ...)

Answer:

Assign the priority considering rule of precedence and associative.

Now read it following manner:

"ptr" is a pointer to an array of size eight, where each element is a pointer to a function. The function takes two parameters: the first one is a pointer to a character constant, and the second one is a variable number of arguments. The return type of the function is a pointer to a pointer of unsigned int data type.

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