---
title: Sunifdef Intro
tags: Sunifdef, Slides
description: the slide to introduct "Sunifdef".
---

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# ++Sunifdef Intro++
Jerry Chen
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slide: https://hackmd.io/@AManTw/Hk-ys3IXS

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## ++什麼是 Sunifdef++

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- 移除C/C++程式碼中，不需要的symbol
- 可一次指定不同值的symbol
- 支援#if...#ifdef...

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## ++#if & #ifdef++
<br>
<style>
code.orange {
color: #B27300 !important;
}
</style>

- <code class="orange">#if</code>&emsp;&nbsp;&nbsp; : 後面接的是判斷式
- <code class="orange">#ifdef</code> : 後面則是接上一個marco

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#if 1
...

#if (MAX > 10)||(MAX < 5)
...


#ifdef RLC_HOST
...

#ifndef RLC_HOST
...

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## ++常用參數-1++

| Var. | 展開範例 | 用途 |
| :---: | :---: | :---: |
| f | -fFILE | 從FILE讀取 symbol|
| r | - -replace | 將結果覆寫至原檔案 |
| D | - -define SYMBOL | 要保留的 SYMBOL |
| U | - -undef SYMBOL | 不保留的 SYMBOL |

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D:代表選擇該symbol是有定義的情況
U:代表選擇該symbol是沒有定義的情況

==> 單純去除symbol外殼的#if #endif => 選 D
==> 要將整塊symbol 包含程式刪除 => 選U

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## ++常用參數-2++

| Var. | 展開範例 | 用途 |
| :---: | :--- | :---: |
| ne[d] | -ne[d] | 判斷#if的真假值 |
| K | - -keepgoing | 錯誤發生時，繼續執行 |
| l | - -line | 印出處理過的行數 |

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## ++實際DEMO++

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#include <stdio.h>

#define _have_define
int num = 1;


void fn_if_zero()
{
    if (num == 0 ) { printf("THis is 0\n"); }
    
#if 0
    else{ printf("Never Go here\n"); }
#else
    else{ printf("GO here\n"); }
#endif
}


void fn_not_defined()
{
    if (num == 0 ){ printf("THis is 0\n"); }
    
#ifndef no_define
    else{ printf("Never go here\n"); }
#else
    else{ printf("no_define is go here \n"); }
#endif
}


void fn_have_define()
{
    if (num == 0 ) { printf("THis is 0\n"); }
    
#ifdef _have_define
    else{ printf("_have_define Go here \n"); }
#else
    else{ printf(" Never Go here\n"); }
#endif
}

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1. #if 0

sunifdef -DDEFINE -ned --replace -l ifdef.c

2. #ifndef

sunifdef -Dno_define --replace -l ifdef.c

3. #ifdef

sunifdef -D_have_define --replace -l ifdef.c 

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### Thank you! :coffee: