char*str="hello";
In this case the string literal is stored in read only memory.
char str[10]="name";
In this case the string literal is stored in writable memory.
Why there is difference in the allocated memory with the two string literals?
In the case of char*str="hello"; (which should really by const char*str="hello";) the actual string literal is stored in read-only memory as an array, and str just points to that. In the second example the array is stored either in the global data segment (for global variables) or on the stack (for local data), there's no pointer.
Think of it like this:
For
const char *str = "hello";
you have
+-----+ +-----------+ | str | ---> | "hello\0" | +-----+ +-----------+
While for
char str[] = "hello";
you have
+-----------+ | "hello\0" | +-----------+
There is no difference with the literals themselves. The difference is with the actual variable you're telling the compiler that you want, str. That variable has different types, and thus the different types have different representations.
In the first case, you say "I want str to be a character pointer, initialized to somewhere (I don't care where) where the string "hello" is to be found".
In the second case you say "I want str to be an array of 10 characters, where the five first are initialized with the string "name".
These are clearly completely different things. It's highly likely that in the program for the second case the string literal "name" still exists in some read-only location but is copied into str when the program starts.
name is copied to str without any command.
int x[2]; x = { 1, 2 };, but you can have int x[2] = { 1, 2};. Same thing, but there is more sugar for strings.It's highly likely that in the program for the second case the string literal "name" still exists in some read-only location but is copied into str when the program starts. ...so does it means that the string literal occupies double memory as it is copied to other location.
char str[10]="name"; initializes all 10 char and not just the first 5, but unable to find a citation - your thoughts?String literals have to come from somewhere within the program when the executable is compiled. Thus they are stored along with the text in a special data segment. Since you don't want to modify the program text each time when executing that segment is mapped into your process VM read-only.
If you need to only read that constant literal then a pointer reference is enough.
But as soon as you need to make modifications to it, then you need to make copies like in your second declaration which will copy that string literal onto the stack upon scope start.
char *strandchar str[]and how both are stored in memorychar str2[] = "hello";simply means an array with string"hello"will be created.