C char array initialization

This is not how you initialize an array, but for:

1. The first declaration:

   char buf[10] = "";
   

   is equivalent to

   char buf[10] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
   

2. The second declaration:

   char buf[10] = " ";
   

   is equivalent to

   char buf[10] = {' ', 0, 0, 0, 0, 0, 0, 0, 0, 0};
   

3. The third declaration:

   char buf[10] = "a";
   

   is equivalent to

   char buf[10] = {'a', 0, 0, 0, 0, 0, 0, 0, 0, 0};
   

As you can see, no random content: if there are fewer initializers, the remaining of the array is initialized with 0. This the case even if the array is declared inside a function.

1. These are equivalent

   char buf[10] = "";
   char buf[10] = {0};
   char buf[10] = {0, 0, 0, 0, 0, 0, 0, 0, 0, 0};
   

2. These are equivalent

   char buf[10] = " ";
   char buf[10] = {' '};
   char buf[10] = {' ', 0, 0, 0, 0, 0, 0, 0, 0, 0};
   

3. These are equivalent

   char buf[10] = "a";
   char buf[10] = {'a'};
   char buf[10] = {'a', 0, 0, 0, 0, 0, 0, 0, 0, 0};