在項目開發中，經常需要讀取應用配置文件的初始化參數，在應用啟前進行一些初始化設置。比如：Eclipse，參數項包含主題、字體大小、顏色、Jdk安裝位置、自動提示等。Eclispe配置的文件格式是以鍵值對的方式存儲的，即：key=value的形式，下面是Eclipse部份設置參數：

/instance/org.eclipse.jdt.ui/useQuickDiffPrefPage=true
/instance/org.eclipse.jdt.ui/content_assist_proposals_foreground=0,0,0
/instance/org.eclipse.egit.core/GitRepositoriesView.GitDirectories=/Users/yangxin/Downloads/kakaolink-android/.git\:/Users/yangxin/Documents/workspace_web/tfyj/.git\:
/instance/org.eclipse.wst.jsdt.ui/fontPropagated=true
/instance/org.eclipse.debug.core/org.eclipse.debug.core.USE_STEP_FILTERS=true
/instance/org.eclipse.jdt.core/org.eclipse.jdt.core.compiler.problem.assertIdentifier=error
/instance/org.eclipse.ui.workbench/org.eclipse.jface.textfont=1|Monaco|14.0|0|COCOA|1|Monaco;
@org.eclipse.jdt.ui=3.8.2.v20130107-165834
/instance/org.eclipse.cdt.ui/spelling_locale_initialized=true

從Eclipse配置文件中可以看出，都是以xxxx=xxxxx，如最後一個配置項，key為/instance/org.eclipse.cdt.ui/spelling_locale_initialized，值為：true。在項目開發當中的也經常采用這種方式，筆者參考了Java的java.util.Properties類，設計了一個C的配置文件讀寫接口，供大家學習和使用。

1、定義接口頭文件（Properties.h）

//
//  Properties.h
//  讀寫配置文件
//
//  Created by 楊信 on 14-4-24.
//  Copyright (c) 2014年 yangxin. All rights reserved.
//

#ifndef _______Properties_h
#define _______Properties_h

#ifdef _cplusplus
extern "C" {
#endif
    
    // 初始化環境，成功返回0，失敗返回非0值
    int init(const char *filepath,void **handle);
    
    // 根據KEY獲取值，找到返回0，如果未找到返回非0值
    int getValue(void *handle, const char *key, char *value);
    
    // 修改key對應的屬性值，修改成功返回0，失敗返回非0值
    int setValue(void *handle, const char *key, const char *value);
    
    // 添加一個屬性，添加成功返回0，失敗返回非0值
    int add(void *handle, const char *key, const char *value);
    
    // 刪除一個屬性，刪除成功返回0，失敗返回非0值
    int del(void *handle, const char *key);
    
    // 獲取屬性文件中所有的key，獲取成功返回0，失敗返回非0值
    int getKeys(void *handle, char ***keys, int *keyscount);
    
    // 釋放所有key的內存空間，成功返回0，失敗返回非0值
    int free_keys(char ***keys,int *keyscount);
    
    // 獲取屬性文件中所有的值，成功返回0，失敗返回非0值
    int getValues(void *handle, char ***values, int *valuescount);
    
    // 釋放所有value的內存空間，成功返回0，失敗返回非0值
    int free_values(char ***values, int *valuescount);
    
    // 獲取屬性數量，成功返回0，失敗返回非0值
    int getCount(void *handle, int *count);
    
    // 釋放環境資源，成功返回0，失敗返回非0值
    int release(void **handle);
    
    
#ifdef _cplusplus
}
#endif

#endif

2、實現頭文件的接口（Properteis.c）

//
//  Properties.c
//  讀寫配置文件
//
//  Created by 楊信 on 14-4-24.
//  Copyright (c) 2014年 yangxin. All rights reserved.
//

#include 
#include 
#include 

#include "Properties.h"

#define KEY_SIZE        128 // key緩沖區大小
#define VALUE_SIZE      128 // value緩沖區大小

#define LINE_BUF_SIZE   256 // 讀取配置文件中每一行的緩沖區大小

typedef struct Properties {
    char *key;
    char *value;
    struct Properties *pNext;
}Properties;

typedef struct PROPS_HANDLE {
    Properties *pHead;  // 屬性鏈表頭節點
    char *filepath;     // 屬性文件路徑
}PROPS_HANDLE;

static int createPropsNode(Properties **props);         // 創建一個節點
static int trimeSpace(const char *src,char *dest);      // 去空格
static int saveConfig(const char *filepath,Properties *head);   // 將修改或保存後的配置項保存到文件

// 初始化環境，成功返回0，失敗返回非0值
int init(const char *filepath,void **handle)
{
    int ret = 0;
    FILE *fp = NULL;
    Properties *pHead = NULL,*pCurrent = NULL, *pMalloc = NULL;
    PROPS_HANDLE *ph = NULL;
    char line[LINE_BUF_SIZE];               // 存放讀取每一行的緩沖區
    char keybuff[KEY_SIZE] = { 0 };         // 存放key的緩沖區
    char valuebuff[VALUE_SIZE] = { 0 };     // 存放value的緩沖區
    char *pLine = NULL;                     // 每行緩沖區數據的指針
    
    if(filepath == NULL || handle == NULL)
    {
        ret = -1;
        printf("fun init error:%d from (filepath == NULL || handler == NULL)\n",ret);
        return ret;
    }
    
    ph = (PROPS_HANDLE *)malloc(sizeof(PROPS_HANDLE));
    if (ph == NULL) {
        ret = -2;
        printf("fun init malloc handle error:%d",ret);
        return ret;
    }
    memset(ph, 0, sizeof(PROPS_HANDLE));
    
    // 打開文件
    fp = fopen(filepath, "r");
    if (!fp) {
        ret = -3;
        printf("fun init open file error:%d from %s\n",ret,filepath);
        return ret;
    }
    
    // 創建頭節點
    ret = createPropsNode(&pHead);
    if (ret != 0) {
        fclose(fp);  // 關閉文件
        printf("fun init create head node error:%d\n",ret);
        return ret;
    }
    memset(pHead, 0, sizeof(Properties));
    
    // 保存鏈表頭節點和文件路徑到handle中
    ph->pHead = pHead;
    ph->filepath = (char *)malloc(strlen(filepath) + 1);
    strcpy(ph->filepath, filepath);
    
    pCurrent = pHead;

    // 讀取配置文件中的所有數據
    while (!feof(fp)) {
        if(fgets(line, LINE_BUF_SIZE, fp) == NULL)
        {
            break;
        }
        
        // 找等號
        if ((pLine = strstr(line, "=")) == NULL) {   // 沒有等號，繼續讀取下一行
            continue;
        }
        
        // 循環創建節點
        ret = createPropsNode(&pMalloc);
        if (ret != 0) {
            fclose(fp);  // 關閉文件
            release((void **)&ph);  // 創建節點失敗，釋放所有資源
            printf("create new node error:%d\n",ret);
            return ret;
        }

        // 設置Key
        memcpy(keybuff, line, pLine-line);
        trimeSpace(keybuff, pMalloc->key);    // 將keybuff去空格後放到pMallock.key中
    
        // 設置Value
        pLine += 1;
        trimeSpace(pLine, valuebuff);
        strcpy(pMalloc->value, valuebuff);
        
        // 將新節點入鏈表
        pMalloc->pNext = NULL;
        pCurrent->pNext = pMalloc;
        pCurrent = pMalloc; // 當前節點下移
        
        // 重置key,value
        memset(keybuff, 0, KEY_SIZE);
        memset(valuebuff, 0, VALUE_SIZE);
    }
    
    // 設置環境句柄給調用者
    *handle = ph;
    
    // 關閉文件
    fclose(fp);
    
    return ret;
}

// 獲取屬性數量，成功返回0，失敗返回非0值
int getCount(void *handle, int *count)
{
    int ret = 0,cn = 0;
    PROPS_HANDLE *ph = NULL;
    Properties *pCurrent = NULL;
    if (handle == NULL || count == NULL) {
        ret = -1;
        printf("fun getCount error:%d from (handle == NULL || count == NULL)\n",ret);
        return ret;
    }
    ph = (PROPS_HANDLE *)handle;
    pCurrent = ph->pHead->pNext;
    while (pCurrent != NULL) {
        cn++;
        pCurrent = pCurrent->pNext;
    }
    
    *count = cn;
    
    return ret;
}

// 根據KEY獲取值，找到返回0，如果未找到返回非0值
int getValue(void *handle, const char *key, char *value)
{
    int ret = 0;
    PROPS_HANDLE *ph = NULL;
    Properties *pCurrent = NULL;
    if (handle == NULL || key == NULL || value == NULL) {
        ret = -1;
        printf("getValue error:%d from (handle == NULL || key == NULL || value == NULL)\n",ret);
        return ret;
    }
    
    ph = (PROPS_HANDLE *)handle;
    pCurrent = ph->pHead->pNext;
    while (pCurrent != NULL) {
        if (strcmp(pCurrent->key,key) == 0) {
            break;
        }
        pCurrent = pCurrent->pNext;
    }
    
    if (pCurrent == NULL) {
        ret = -2;
        printf("fun getValue warning: not found the key:%s\n",key);
        return ret;
    }
    
    strcpy(value, pCurrent->value);
    
    return ret;
}

// 修改key對應的屬性值，修改成功返回0，失敗返回非0值
int setValue(void *handle, const char *key, const char *value)
{
    int ret = 0;
    PROPS_HANDLE *ph = NULL;
    Properties *pCurrent = NULL;
    if (handle == NULL || key == NULL || value == NULL) {
        ret = -1;
        printf("fun setValue error:%d from (handle == NULL || key == NULL || value == NULL)\n",ret);
        return ret;
    }
    
    // 獲得環境句柄
    ph = (PROPS_HANDLE *)handle;
    
    // 從環境句柄中獲取頭節點
    pCurrent = ph->pHead->pNext;
    while (pCurrent != NULL) {
        if (strcmp(pCurrent->key, key) == 0) {  // 找到
            break;
        }
        pCurrent = pCurrent->pNext;
    }
    
    if (pCurrent == NULL) { // 未找到key
        ret = -2;
        printf("fun setValue warning: not found the key:%s\n",key);
        return ret;
    }
    
    // 修改key的value
    strcpy(pCurrent->value, value);
    if (strchr(value, '\n') == NULL) {  // 加一個換行符
        strcat(pCurrent->value, "\n");
    }
    
    // 將修改的配置項寫入到文件
    ret = saveConfig(ph->filepath, ph->pHead);
  
    return ret;
}

// 添加一個屬性，添加成功返回0，失敗返回非0值
int add(void *handle, const char *key, const char *value)
{
    int ret = 0;
    PROPS_HANDLE *ph = NULL;
    Properties *pCurrent = NULL;
    if (handle == NULL || key == NULL || value == NULL) {
        ret = -1;
        printf("fun add error:%d from (handle == NULL || key == NULL || value == NULL)\n",ret);
        return ret;
    }
    
    ph = (PROPS_HANDLE *)handle;
    
    //-----------如果key存在鏈表中，則直接修改，否則添加到鏈表中-----------//
    pCurrent = ph->pHead;
    while (pCurrent->pNext != NULL) {
        if (strcmp(pCurrent->pNext->key,key) == 0) {
            break;
        }
        pCurrent = pCurrent->pNext;
    }
    
    if (pCurrent->pNext != NULL) {
        return setValue(handle, key, value);
    }
    
    //-----------key不存在，創建一個新的配置項，添加到鏈表中-----------//
    Properties *pMalloc;
    ret = createPropsNode(&pMalloc);
    if (ret != 0) {
        printf("fun add error:%d from malloc new node.",ret);
        return ret;
    }
    
    strcpy(pMalloc->key, key);
    if (strchr(pCurrent->value,'\n') == NULL) {
        strcat(pCurrent->value, "\n");
    }
    strcpy(pMalloc->value, value);
    if (strchr(value, '\n') == NULL) {  // 加一個換行符
        strcat(pMalloc->value, "\n");
    }
    pCurrent->pNext = pMalloc;  // 新配置項入鏈表
    
    // 將新配置項寫入到文件
    ret = saveConfig(ph->filepath, ph->pHead);
    
    return ret;
}

// 刪除一個屬性，刪除成功返回0，失敗返回非0值
int del(void *handle, const char *key)
{
    int ret = 0;
    PROPS_HANDLE *ph = NULL;
    Properties *pCurrent = NULL, *pPrev = NULL;
    if (handle == NULL || key == NULL) {
        ret = -1;
        printf("fun del error:%d from (handle == NULL || key == NULL)\n",ret);
        return ret;
    }
    
    ph = (PROPS_HANDLE *)handle;
    pPrev = ph->pHead;
    pCurrent = ph->pHead->pNext;
    
    while (pCurrent != NULL) {
        if (strcmp(pCurrent->key, key) == 0) {
            break;
        }
        pPrev = pCurrent;           // 上一個節點下移
        pCurrent = pCurrent->pNext; // 當前節點下移
    }
    
    if (pCurrent == NULL) { // 沒有找到
        ret = -2;
        printf("fun del warning:not found the key:%s\n",key);
        return  ret;
    }
    
    pPrev->pNext = pCurrent->pNext; // 從鏈表中刪除
    free(pCurrent); // 釋放內存
    pCurrent = NULL;
    
    // 保存到文件
    ret = saveConfig(ph->filepath, ph->pHead);
    
    return ret;
}

// 獲取屬性文件中所有的key，獲取成功返回0，失敗返回非0值
int getKeys(void *handle, char ***keys, int *keyscount)
{
    int ret = 0, count = 0, index = 0;
    PROPS_HANDLE *ph = NULL;
    Properties *pCurrent = NULL;
    char **pKeys = NULL;
    if (handle == NULL || keys == NULL || keyscount == NULL) {
        ret = -1;
        printf("fun getKeys error:%d from (handle == NULL || keys == NULL || keyscount == NULL) \n",ret);
        return ret;
    }
    
    // 獲取配置項數量
    ret = getCount(handle, &count);
    if (ret != 0) {
        printf("fun getKeys error:%d from getCount \n",ret);
        return ret;
    }
    
    ph = (PROPS_HANDLE *)handle;
    pCurrent = ph->pHead->pNext;
    
    // 根據鏈表長度，申請內存空間
    pKeys = (char **)malloc(sizeof(char *) * count);
    if (pKeys == NULL) {
        ret = -2;
        printf("fun getKeys error:%d from malloc keys\n",ret);
        return ret;
    }
    
    pCurrent = ph->pHead->pNext;
    while (pCurrent != NULL) {
        pKeys[index] = pCurrent->key;
        pCurrent = pCurrent->pNext;
        index++;
    }
    
    *keys = pKeys;
    *keyscount = count;
    
    return ret;
}

// 釋放所有key的內存空間，成功返回0，失敗返回非0值
int free_keys(char ***keys,int *keyscount)
{
    int ret = 0;
    if (keys == NULL || keyscount == NULL) {
        ret = -1;
        printf("fun free_keys error:%d from (keys == NULL || keyscount == NULL) \n",ret);
        return ret;
    }
    
    free(*keys);
    *keys = NULL;
    *keyscount = 0;
    
    return ret;
}

// 獲取屬性文件中所有的值，成功返回0，失敗返回非0值
int getValues(void *handle, char ***values, int *valuescount)
{
    int ret = 0, count = 0, index = 0;
    PROPS_HANDLE *ph = NULL;
    Properties *pCurrent = NULL;
    char **pValues = NULL;
    if (handle == NULL || values == NULL || valuescount == NULL) {
        ret = -1;
        printf("fun getValues error:%d from (handle == NULL || values == NULL || valuescount == NULL)\n",ret);
        return ret;
    }
    
    // 獲取配置項數量
    ret = getCount(handle, &count);
    if (ret != 0) {
        printf("fun getValues error:%d from getCount \n",ret);
        return ret;
    }
    
    // 申請內存空間，存放所有的value
    pValues = (char **)malloc(sizeof(char *) * count);
    if (pValues == NULL) {
        ret = -2;
        printf("fun getValues error:%d from malloc values\n",ret);
        return ret;
    }
    
    ph = (PROPS_HANDLE *)handle;
    pCurrent = ph->pHead->pNext;
    while (pCurrent != NULL) {
        pValues[index] = pCurrent->value;
        pCurrent = pCurrent->pNext;
        index++;
    }
    
    *values = pValues;
    *valuescount = count;
    
    return ret;
}

// 釋放所有value的內存空間，成功返回0，失敗返回非0值
int free_values(char ***values, int *valuescount)
{
    int ret = 0;
    if (values == NULL || valuescount == NULL) {
        ret = -1;
        printf("fun free_values error:%d from (values == NULL || valuescount == NULL) \n",ret);
        return ret;
    }
    
    free(*values);
    *values = NULL;
    *valuescount = 0;
    
    return ret;
}

// 釋放環境資源，成功返回0，失敗返回非0值
int release(void **handle)
{
    int ret = 0;
    PROPS_HANDLE *ph = NULL;
    if(handle == NULL)
    {
        ret = -1;
        printf("release error:%d from (handler == NULL)\n",ret);
        return ret;
    }
    
    ph = (PROPS_HANDLE *)*handle;
    
    // 釋放鏈表內存資源
    Properties *pCurr = ph->pHead;
    Properties *pTemp = NULL;
    
    while (pCurr != NULL) {
        if (pCurr->key != NULL) {
            free(pCurr->key);
            pCurr->key = NULL;
        }
        
        if (pCurr->value != NULL) {
            free(pCurr->value);
            pCurr->value = NULL;
        }
        
        pTemp = pCurr->pNext;
        
        free(pCurr);
        
        pCurr = pTemp;
    }
    
    // 釋放存放配置文件路徑分配的內存空間
    if(ph->filepath != NULL)
    {
        free(ph->filepath);
        ph->filepath = NULL;
    }
    
    // 釋放環境句柄本身
    free(ph);
    *handle = NULL;    // 避免野指針
        
    return ret;
}

// 去空格
static int trimeSpace(const char *src,char *dest)
{
    int ret = 0;
    if (src == NULL || dest == NULL) {
        ret = -1;
        printf("trimeSpace error:%d from (src == NULL || dest == NULL)\n",ret);
        return ret;
    }
    
    const char *psrc = src;
    unsigned long i = 0,j = strlen(psrc) - 1,len;
    while (psrc[i] == ' ')
    {
        i++;
    }
    
    while (psrc[j] == ' ') {
        j--;
    }
    
    len = j - i + 1;
    
    memcpy(dest,psrc+i,len);
    *(dest+len) = '\0';
    
    return ret;
}

// 創建一個節點
static int createPropsNode(Properties **props)
{
    int ret = 0;
    Properties *p = NULL;
    if (props == NULL) {
        ret = -100;
        printf("createProps error:%d from (props == NULL)\n",ret);
        return ret;
    }
    
    p = (Properties *)malloc(sizeof(Properties));
    if (p == NULL) {
        ret = -200;
        printf("createProps malloc %ld bytes error:%d\n",sizeof(Properties),ret);
        return ret;
    }
    p->key = (char *)malloc(KEY_SIZE);
    p->value = (char *)malloc(VALUE_SIZE);
    p->pNext = NULL;
    
    *props = p;
    
    return ret;
}

// 保存到文件
static int saveConfig(const char *filepath,Properties *head)
{
    int ret = 0,writeLen = 0;
    FILE *fp = NULL;
    Properties *pCurrent = NULL;
    if (filepath == NULL || head == NULL) {
        ret = -100;
        printf("fun saveConfig error:%d from (filepath == NULL || head == NULL)\n",ret);
        return ret;
    }
    
    fp = fopen(filepath,"w");
    if (fp == NULL) {
        ret = -200;
        printf("fun saveConfig:open file error:%d from %s\n",ret,filepath);
        return ret;
    }
    
    pCurrent = head->pNext;
    while (pCurrent != NULL) {
        writeLen = fprintf(fp, "%s=%s",pCurrent->key,pCurrent->value);    // 返回寫入的字節數，出現錯誤返回一個負值
        if (writeLen < 0) {  //TODO 如果寫入失敗，如何將寫入的數據回退？？？
            ret = -300;
            printf("fun saveConfig err:%d from (%s=%s)\n",ret,pCurrent->key,pCurrent->value);
            break;
        }
        pCurrent = pCurrent->pNext;
    }

    fclose(fp); // 關閉文件
    
    return ret;
}

3、測試代碼（需要在項目根目錄創建props.txt）

//
//  main.c
//  讀寫配置文件
//
//  Created by 楊信 on 14-4-24.
//  Copyright (c) 2014年 yangxin. All rights reserved.
//

#include 
#include 
#include 
#include "Properties.h"

int main(int argc, const char * argv[])
{
    int ret;
    void *handle;
    const char *filepath = "/Users/yangxin/Desktop/props.txt";
    // 初始化
    ret = init(filepath, &handle);
    if (ret != 0) {
        printf("env init error:%d\n",ret);
        return 0;
    }
    
    char valuebuf[128];
    // 測試獲取配置項
    ret = getValue(handle, "host", valuebuf);
    if (ret == 0) {
        printf("value=%s\n",valuebuf);
    }
    else {
        printf("獲取值host的值失敗\n");
    }
    
    // 測試修改配置項
    ret = setValue(handle, "version", "1.2.3");
    if (ret == 0) {
        printf("修改成功!\n");
    }
    else{
        printf("修改失敗\n");
    }
    
    // 測試添加配置項
    ret = add(handle, "pool_connection_countxx", "2000");
    if (ret == 0) {
        printf("添加成功!\n");
    }
    else{
        printf("添加失敗\n");
    }
    
    // 測試刪除配置項
    ret = del(handle, "connectionMax");
    if (ret == 0) {
        printf("刪除成功!\n");
    }
    else{
        printf("刪除失敗\n");
    }
    
    // 測試獲取所有配置項的key
    char **keys = NULL;
    int keyscount;
    ret = getKeys(handle, &keys, &keyscount);
    if (ret == 0) {
        printf("一共有%d個Key\n",keyscount);
        for (int i =0; i

測試配置文件：


username=root
password=root123456
host=192.168.1.100
port=9090
connectionMax=200
version=1.0

測試結果：
下載地址：[email protected]:xyang0917/RWAppProperites.git