Why Do C and C Require Short Variables to Be Converted to Int Before Arithmetic Operations?

Why Short Variables Require Conversion to Int for Arithmetic Operations in C and C

Despite inheriting this requirement from C, C mandates the conversion of short variables to int before arithmetic operations due to historical reasons.

The rationale behind this stems from the two main camps in C implementations: unsigned preserving and value preserving. Unsigned preserving promotes short to unsigned int, while value preserving promotes it to signed int if it can represent all short values, otherwise to unsigned int.

This approach was adopted to accommodate the varying representations of short across execution environments. By always converting to int, calculations are performed in a wider type, often producing smaller and faster code, as well as the correct result more frequently.

For instance, consider:

short s = 1, t = 2;
auto x = s + t;

Here, x will have the type int because the integer promotions convert s and t to int before performing the addition. Allowing calculations in narrow types (e.g., short) might lead to unexpected results or incorrect answers. Therefore, the conversion to int ensures consistent behavior and optimal performance.

The above is the detailed content of Why Do C and C Require Short Variables to Be Converted to Int Before Arithmetic Operations?. For more information, please follow other related articles on the PHP Chinese website!