Difference between using character pointers and character arrays

Question

Basic question.

char new_str[]=\"\";

char * newstr;

If I have to concatenate some data into it or use string functions like strcat/substr/

Answer 1

The type of the first is char[1], the second is char *. Different types.

Allocate memory for the latter with malloc in C, or new in C++.

char foo[] = "Bar";  // Allocates 4 bytes and fills them with
                     // 'B', 'a', 'r', '\0'.

The size here is implied from the initializer string.

The contents of foo are mutable. You can change foo[i] for example where i = 0..3.

OTOH if you do:

char *foo = "Bar";

The compiler now allocates a static string "Bar" in readonly memory and cannot be modified.

foo[i] = 'X';  // is now undefined.