When and How Are Variables Automatically Initialized in C ?

Variable Initialization in C : When and Where Does It Occur Automatically?

Understanding variable initialization in C is crucial for developing robust code. Contrary to the assumption that int variables are automatically initialized to 0, the following code snippet demonstrates that this is not the case:

int main () {
    int a[10];
    int i;
    cout <p>This code will output a random value for the uninitialized variable i. To address this, it is essential to understand the rules governing initialization in C  .</p><p><strong>Automatic Initialization Rules</strong></p><p>In C  , variables are automatically initialized only under specific conditions:</p>

• Class/Struct Instances: Default constructor initialization will initialize all primitive types within a class or struct instance.
• Array Initializer Syntax: Using curly braces to initialize arrays, e.g., int a[10] = {} or int a[10] = {1,2}, will automatically zero out any uninitialized elements.
• Global/Extern Variables: Variables declared outside of function scope (global or extern) are automatically initialized to 0.
• Static Variables: Variables with the static keyword are automatically initialized to 0, regardless of their scope.

The above is the detailed content of When and How Are Variables Automatically Initialized in C ?. For more information, please follow other related articles on the PHP Chinese website!