Data types are ordered according to the largest magnitude they can represent. For example, int32_t is obviously "larger" than int16_t. But this also means that unsigned integers are always larger than signed integers of the same size.

Promotion occurs when a value is copied to a larger data type. Demotion occurs when a value is copied to a smaller data type.

In either case, information may be lost if the value cannot be represented in the new data type - either because the number of bits is insufficient, or because a negative value is copied to an unsigned integer.

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