C program to find size...can anyone tell me how this program works?

Question

Size of
https://code.sololearn.com/c4K8cykTcAx3/?ref=app

Answer 1

sizeof returns the memory size of the value you pass to it.

unsigned size1 = sizeof(10.2);

returns 8, because the number is of type double which is of size 8 (bytes).

unsigned size2 = sizeof(010);

returns 4 because 010 is an octal number literal, which translates to a normal int which is of size 4.

Most interesting is line 3:

unsigned size3 = sizeof(ch+d);

ch is a char, which is of size 1, but d is a double.

When you add two numbers (char is represented as a letter, but internally it is a number) of different types, the smaller type is 'upgraded' first, so the result will be of the larger type, in this case double, so 8 bytes.

Answer 2

An int variable, for example, is typically allocated 4 bytes when declared. We know this by using the sizeof operator:
Exam:
int x;
Printf ("%d" , sizeof (x));