c++ - initialize char array with quotes and curly braces -

i'm little confused. logically difference between these codes?

#include <iostream> using namespace std; int main(){     char a[5]="abcd"; //     cout << a;     return 0; } 

second is

char a[5]={"abcd"}; // 

third is

char a[5]={'a','b','c','d'}; // 

char a[5]={"abcd"}; char a[5]={'a','b','c','d','\0'}; 

in both cases, array of characters a declared size of 5 elements of type char: 4 characters compose word "abcd", plus final null character ('\0'), specifies end of sequence , that, in second case, when using double quotes (") appended automatically.attention adding null character separating via commas. series of characters enclosed in double quotes ("") called string constant. c compiler can automatically add null character '\0' @ end of string constant indicate end of string.

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