How Are Arrays Initialized with Braces in C and C ?

Array Initialization with Braces: Unveiling the Compiler's Behavior

In programming, assigning an array with curly braces, such as array[100] = {0}, raises questions about how the values are initialized internally. Let's delve into the wizardry behind this notation.

Magic or Compiler Logic?

Contrary to common perception, there's no magic involved. The behavior of this code is governed by programming language specifications:

C Specification (section 6.7.8.21): For unspecified array elements, pointers are initialized to NULL, and arithmetic types (including char) are set to zero.

C Specification (section 8.5.1.7): Unspecified array elements are aggregate-initialized.

Empty Initializer List in C : C supports empty initializer lists like array[100] = {};, which aggregate-initialize all elements of the array.

Compiler-Generated Code: Typically, compilers generate code that sets each element of the array to the specified value. However, depending on the compiler and optimization settings, the code can vary.

For further insight into the compiler's behavior, refer to the assembly code generated for empty initializer lists in the related question: "Strange assembly from array 0-initialization."

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