According to the WG14 document:
Given an integer expression E, the derived type T of E is determined as follows:
- if E is a sizeof expression, then T is the type of the operand of the expression;
- otherwise, if E is an identifier, then T is the derived type of the expression last used to store a value in E;
- otherwise, if the derived type of each of E's subexpressions is the same, then T is that type;
- otherwise, the derived type is an unspecified character type compatible with any of char, signed char, and unsigned char.
Note: The first rule from the above definition is applied to non-compliant code/compliant solution 2 and 4 in this page to calculate the derived type of expression 'n' is those examples.
Effective size of a pointer is the size of the object to which it points.
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Example: int arr\[5\]; |
int *p = arr;
The effective size of the pointer 'p' in this example will be sizeof(arr) i.e. 5*sizeof(int).
Effective type of an object is
Description
According to C standard - 6.2.5 Types,
C library functions that make changes to arrays or objects usually take at least two arguments: i.) a pointer to the array/object ii.) an integer indicating the number of elements or bytes to be manipulated. If the arguments are supplied improperly during such a function call, the function may cause the pointer to not point to the object at all or point past the end of the object. This would lead to undefined behavior.
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API00-C. Functions should validate their parameters - https://www.securecoding.cert.org/confluence/display/seccode/API00-C.+Functions+should+validate+their+parameters
WG14 Document: N1579 - Rule 5.34 Forming Invalid pointers by library functions.
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