c - initializing array of structure with array elements in it -

#include <stdio.h>  int main() {     typedef struct s     {         int a;         int b[5];         char c[2];     }st;      st vs[1];      vs[0] = {1,{1,2,3,4,5},{'c','d'}};      printf("%d:a\n",vs[1].a);     printf("%d:b[0]\t %d:b[4]\n",vs[0].b[0],vs[0].b[4]);     printf("%c:c[0]\t %c:c[1]\n",vs[0].c[0],vs[0].c[1]);      return 0; } 

why doesn't work?

on

gcc -o main *.c  

i error

main.c: in function 'main': main.c:15:12: error: expected expression before '{' token vs[0] ={1,{1,2,3,4,5},{'c','d'}};

but if have this:

#include <stdio.h>  int main() {     typedef struct s     {         int a;         int b[5];         char c[2];     }st;      st vs[] = {                 {1,{1,2,3,4,5},{'c','d'}}               };      printf("%d:a\n",vs[0].a);     printf("%d:b[0]\t %d:b[4]\n",vs[0].b[0],vs[0].b[4]);     printf("%c:c[0]\t %c:c[1]\n",vs[0].c[0],vs[0].c[1]);      return 0; } 

it works. logic in this.

how can make work using st vs[1] method?

initialization when declare variable , provide initial values part of declaration. example legal:

st vs[1] = { {1,{1,2,3,4,5},{'c','d'}} }; 

your code attempting assignment. assignment when existing variable has value assigned it. reason code doesn't work {1,{1,2,3,4,5},{'c','d'}} isn't value.

in statement (not declaration), each expression must readable compiler on own merit, , more complicated statement made of various expressions joined operators. compiler doesn't know {1,{1,2,3,4,5},{'c','d'}} - @ stage has no idea that supposed st.

since c99 there new language construct can use here, called compound literal:

vs[0] = (const st){1,{1,2,3,4,5},{'c','d'}}; 

note not cast operator being applied sort of braced expression; single syntactic construct (typename){ initializers } .

my use of const micro-optimization, may compiler store literal in read-only block of executable , allow constant folding.