How Do You Efficiently Initialize Memory Allocated with the `new` Operator in C ?

Initialising Memory with the New Operator in C

In C , the new operator allocates memory dynamically. Newcomers often face the challenge of efficiently initialising allocated memory without resorting to manual looping. This question explores the optimal way to accomplish this task.

Memset vs. C Syntax

One option is to use memset, a function that sets a block of memory to a specified value. However, C provides a more elegant solution for value-initialisation:

new int[10]();

This syntax initialises an array of type int with ten elements, all set to 0. It utilises the special syntax () to signal value-initialisation.

ISO C Standard

The ISO C 03 standard explicitly allows this behaviour in section 5.3.4[expr.new]/15. It states that a new-expression with an initialiser of the form () initialises the object with the value initialiser (8.5). This includes arrays without any restrictions.

Advantages

This syntax simplifies initialisation, especially for large arrays. It also ensures proper value-initialisation, which is important for correctness and avoiding undefined behaviour. As a result, it is recommended as the "C " way to initialise memory allocated with new.

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