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Does int a = int(); necessarily give me a zero?
How about if int is replaced by char, double, bool or pointer type?
Where is this specified in the language standard, please?
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It is used in all the standard conversions. For example conversion of binary to decimal, octal to decimal, hexadecimal to decimal. How to Convert Bytes to Int in Python?
What does (int*) p mean? (int *) p is an explicit type casting for the value stored in variable p, to the type of a pointer whose address points to an integer. The value that p stores is a memory address of the 1st byte of the 4 that are used to store said 32 bit (4 byte) integer.
malloc () returns a pointer of type void *, and (int *) denotes a type cast that explicitly converts the pointer’s type to int *. In C (but not C++), this conversion would happen implicitly even without the cast. So the next question to ask should be: is it good programming style to write this cast explicitly?
Zero correlation implies independence if the variables are multivariate normal. This is not the same as each variable being normal - see here for some scatterplots of zero-correlated but dependent normal variables (each variable is individually normal) – Glen_b -Reinstate Monica Oct 31 '15 at 8:55
Does
int a = int();necessarily give me a zero?
Yes, the standard guarantees that it gives you zero.
This is known as Value Initialization. For the type int, Value Initialization basically ends up being an Zero Initialization.
Where is this specified in the language standard, please?
The rules are clearly specified in the standard in section 8.5. I will quote the relevant ones to the Q here:
C++03: 8.5 Initializers
Para 7:
An object whose initializer is an empty set of parentheses, i.e., (), shall be value-initialized.
Value Initialization & Zero Initialization are defined in 8.5 Para 5 as:
To value-initialize an object of type T means:
— if T is a class type (clause 9) with a user-declared constructor (12.1), then the default constructor for T is called (and the initialization is ill-formed if T has no accessible default constructor);
— if T is a non-union class type without a user-declared constructor, then every non-static data member and base-class component of T is value-initialized;
— if T is an array type, then each element is value-initialized;
— otherwise, the object is zero-initializedTo zero-initialize an object of type T means:
— if T is a scalar type (3.9), the object is set to the value of 0 (zero) converted to T;
— if T is a non-union class type, each nonstatic data member and each base-class subobject
is zero-initialized;
— if T is a union type, the object’s first named data member is zero-initialized;
— if T is an array type, each element is zero-initialized;
— if T is a reference type, no initialization is performed.
Note: The bold texts are emphasized by me.
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