cfg.h

#pragma once
#include <iostream>
#include <string>
#include <cstring>
using namespace std;

struct CFG_J
{
    string key;//索引
    string value;//值
    CFG_J *next;//下個結點
};
class Config
{
private:
    string file_name;//文件名字
    CFG_J * head;//頭指針
    int cfg_line;//配置行數
    int createHead();//
 
創建一個鏈表頭指針
    int freeJoin();//釋放鏈表的節點
    int inputFile();//內存配置同步配置到文件
    int joinHead(string key, string value);//將某個配置加入到鏈表中
public:
    Config(string file_name);//構造函數
    ~Config();//析構函數
    int getLines();//獲取配置數量
    int setCFG(string key, string value);//設置一個配置
    string getCFG(string key);//從內存獲取某個配置的值
 

    int getCFG();//從文件獲取所有的配置 加載入內存鏈表
    void printCfg();//打印配置鏈表內容
};

cfg.cpp

#include "cfg.h"
#include <fstream>

//構造函數
Config::Config(string file_name)
{
    //定義一個配置文件
    this->file_name = file_name;
    //默認一共0個配置
    this->cfg_line = 0;
    if (createHead() == 0)
    {
        //從文件讀取全部配置 加入鏈表
 

        getCFG();
        //打印全部配置
        //printCfg();
    }
}

//析構函數
Config::~Config()
{
    //釋放鏈表的各個節點
    freeJoin();
    //釋放頭節點
    if (this->head != NULL)
    {
        delete this->head;
    }
}

//獲取配置的總數
int Config::getLines()
{
    return this->cfg_line;
}

//設置某個配置項
int Config::setCFG(string key, string value)
{
    int rt = 0;
    //插入鏈表
    joinHead(key, value);
    //同步到文件
    inputFile();
    return rt;
}

//內存配置同步到文件
int Config::inputFile()
{
    int rt = 1;
    if (this->head == NULL)
    {
        return rt;
    }
    //緩存字符串
    string st;
    //定義文件類型
    ofstream outfile;
    //打開文件方式
    outfile.open(this->file_name , ios::out | ios::trunc);
    // 遍歷向文件寫入用戶輸入的數據
    CFG_J * p = this->head->next;
    while (p != NULL)
    {
        //定義字符串
        st = p->key + "=" + p->value;
        //寫入字符串
        outfile << st << endl;
        //移動指針
        p = p->next;
    }
    //關閉文件
    outfile.close();
    return rt;
}

//獲取某項特定配置
string Config::getCFG(string key)
{
    //默認找不到
    string rt = "CANNOT FIND THIS CONFIG.";
    if (this->head == NULL)
    {
        return rt;
    }
    //遍歷抓取配置項
    CFG_J *p = this->head->next;
    while (p != NULL)
    {
        if (p->key.compare(key) == 0)
        {
            //捕捉到則返回值
            rt = p->value;
            break;
        }
        p = p->next;
    }
    return rt;
}

//從文件獲取全部的配置
int Config::getCFG()
{
    int rt = 0;
    //先清空鏈表
    freeJoin();
    //配置總數為0
    this->cfg_line = 0;
    //定義緩存字符串變量
    string st;
    string key, value;
    //定義文件變量
    ifstream infile;
    string::size_type idx;
    char *p = NULL, *q = NULL;
    //打開文件
    infile.open(this->file_name);
    //遍歷直到文件的最後
    while (!infile.eof())
    {
        //初始化緩存
        st = "";
        //取得一行配置
        infile >> st;
        //找不到等號則繼續
        idx = st.find("=");
        if (idx == string::npos)
        {
            continue;
        }
        //截斷字符串得到key和value字符串
        key = st.substr(0, idx);
        value = st.substr(idx + 1,st.length()-idx);
        //插入鏈表
        joinHead(key,value);
    }
    //關閉文件
    infile.close();
    return rt;
}

//將配置插入內存鏈表
int Config::joinHead(string key,string value)
{
    int rt = 1;
    if (this->head == NULL)
    {
        rt = 2;
        return rt;
    }
    //定義移動指針
    CFG_J * p = this->head;
    CFG_J * cur = p->next;
    while (cur != NULL)
    {
        //cout << cur->key << " " << key << " " << cur->key.compare(key) << endl;
        //找到值則直接改變
        if (cur->key.compare(key) == 0)
        {
            cur->value = value;
            rt = 0;
            break;
        }
        p = cur;
        cur = p->next;
    }
    //找不到值則再最後插入
    if (rt != 0)
    {
        CFG_J *q = new CFG_J();
        q->key = key;
        q->value = value;
        q->next = NULL;
        p->next = q;
        //配置數自增
        this->cfg_line ++;
    }
    return rt;
}

//釋放全部節點（除了頭指針）
int Config::freeJoin()
{
    int rt = 1;
    //定義移動指針
    CFG_J * p = this->head->next;
    CFG_J * cur = p;
    if (p == NULL)
    {
        return rt;
    }
    //遍歷釋放內存
    while (cur != NULL)
    {
        p = cur->next;
        delete cur;
        cur = p;
    }
    //初始化頭指針
    this->head->next = NULL;
    rt = 0;
    return rt;
}

//打印所有的配置
void Config::printCfg()
{
    if (this->head == NULL)
    {
        return;
    }
    //定義移動指針
    CFG_J * p = this->head->next;
    while (p != NULL)
    {
        cout << p->key << "=" << p->value << endl;
        //移動指針
        p = p->next;
    }
}

//創建配置鏈表頭指針
int Config::createHead()
{
    int rt = 1;
    CFG_J *p = new CFG_J();
    p->key = "headkey";
    p->value = "headvalue";
    p->next = NULL;
    this->head = p;
    rt = 0;//沒有問題
    return rt;
}

main.cpp

#include <iostream>
#include "cfg.h"
using namespace std;

#define FILE_PATH "cfg.txt"

int main()
{
    string key;
    string value;
    Config cfg(FILE_PATH);
    /*cout << "Writing to the file" << endl;
    cout << "Enter your key: ";
    cin >> key;
    cout << "Enter your value: ";
    cin >> value;
    cfg.setCFG(key,value);*/
    cout << cfg.getLines() << endl;
    cout << "name=" << cfg.getCFG("name") << endl;
    cout << cfg.getCFG("cxx") << endl;
    system("pause");
}

c++配置文件讀取、修改、添加