How Can I Initialize All Elements of a C Array to a Specific Non-Zero Value?

Initialization of Arrays to a Default Value in C

When initializing arrays in C , using the syntax int array[100] = {-1}; sets only the first element to the specified value, while the remaining elements are initialized to 0. This is because the syntax {} initializes only the first element, leaving the rest to be initialized with default values.

To initialize all elements to a specific non-zero value, such as -1, the std::fill_n function from the header can be used:

std::fill_n(array, 100, -1);

Alternatively, in portable C without the std::fill_n function, a loop can be used:

for (int i = 0; i < 100; i++) {
  array[i] = -1;
}

Regarding performance, initializing the array with a non-zero value through the std::fill_n function or a loop does not have a significant performance difference compared to using the {} syntax for a value of 0. In either case, the compiler optimizes the initialization process.

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