What is the Difference Between \'register\' and \'int\' in C ?

The Distinction between 'register' and 'int' in C

When declaring a variable in C , developers can employ the 'register' keyword to hint to the compiler that a specific variable should reside in a processor register rather than in memory. For instance, consider the following code:

int x = 7;

and:

register int x = 7;

The difference between the two examples lies in the usage of the 'register' keyword. In the first case, the 'x' variable is declared as an integer and will reside in memory. In the second case, the 'register' keyword suggests to the compiler that it would be beneficial to store 'x' in a processor register.

However, it's crucial to note that the compiler has the discretion to disregard this suggestion. As Herb Sutter asserts in "Keywords That Aren't (or, Comments by Another Name)":

"A register specifier has the same semantics as an auto specifier..."

In other words, using 'register' simply directs the compiler to allocate 'x' in a manner similar to the 'auto' keyword, which has no specific implications for the variable's location. Therefore, while 'register' conveys a preference for register storage, its actual implementation is at the compiler's discretion.

The above is the detailed content of What is the Difference Between \'register\' and \'int\' in C ?. For more information, please follow other related articles on the PHP Chinese website!