Question on storing a string inside a struct member in c-CodePudding

Can someone explain

Why does the below code work for saving a string in a struct member

struct prefix {
    char aString[70];
};

struct prefix data={
  .aString = "d08430c90b467422ae9bf7f8ecf8a77682f92764efe53e0ebe26d4ffb6fb96bf"
 };

while the code below does not?

struct prefix {
    char aString[70];
};

struct prefix data;

data.aString = "d08430c90b467422ae9bf7f8ecf8a77682f92764efe53e0ebe26d4ffb6fb96bf"; 
              //Array type 'char [70]' is not assignable

CodePudding user response：

initialization: create an object and specify its value in one instruction;
assignment: change the value of a pre-existing object

struct prefix data = { ... }; // initialization;
struct prefix data; // not initialized now, cannot ever initialize it later, only assign