Difference Between   char* s   and   char s[]   and   char s[n]

This page answers questions like these:

• What’s the difference between   char* s   and   char s[]   in C/C++?
  
• What’s the difference between   char s[]   and   char s[n]   in C/C++?
  
• What’s the difference between   char s[n]   and   char* s   in C/C++?
  

Difference Between   char* s   and   char s[]   and   char s[n]

• Create a character pointer s (which is uninitialized).
• You can change the value of s.  i.e. You can make it point to something else.
• sizeof(s) == sizeof(char*).

• Invalid as a stand-alone variable! This is not valid C++ or C. (See below for valid usage inside a struct or function.)

• Create an array s of 5 characters. The array elements are uninitialized.
• You can’t change the value of s.  i.e. You can’t make it point to something else.
• sizeof(s) == 5   because there are 5 characters in the array.

• Declare a struct type containing a character pointer s.
• In any variable of this type, the element s is uninitialized.
• You can change the value of s.  i.e. You can make it point to something else.
• sizeof(MyStruct) == sizeof(char*)   because s is a variable of type char*.

• Declare a struct containing an array s of characters of unknown length. i.e. The variable s is merely another name for the first memory location in the struct.
• You can’t change the value of s.  i.e. You can’t make it point to something else.
• sizeof(MyStruct) == 0   because s is merely a name for a memory location, not a variable.

• Declare a function taking a char* and returning an int.
• There is no difference between these two function declarations.