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為什麼C和C ++在算術操作期間會促進`short''Int'?

發佈於2025-03-12
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Why Do C and C   Promote `short` to `int` During Arithmetic Operations?
為什麼在C和C?

Integer Promotions

的背景在C中,Integer促銷是在表達式中自動轉換的,以確定數據類型在表達式中自動轉換。適用於算術表達式的通常的算術轉換涉及將其促進到INT,如果它可以代表所有簡短值。 Otherwise, it is promoted to unsigned int.

Rationale for Wider Calculations

According to the C standard rationale, allowing calculations in wider types than necessary was introduced to:

Generate smaller and faster code

Provide more accurate results

This design decision is attributed to the varying hardware architectures at the time, where using wider types could result in more efficient code execution.

Implications for Short Operands
  • When a short operand is encountered in an arithmetic operation, it undergoes integer promotions.此促銷通常會將其轉換為INT,它提供了更大的值範圍,並確保操作的一致數據類型。
  • 考慮以下代碼spippet:
  • 在這裡,s和t是簡短的類型。但是,它們添加的結果存儲在X中,該X具有INT類型。這與C標準中定義的通常的算術轉換和整數促銷相一致。
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