一个使用C++读取INI格式配置文件的练习

最新推荐文章于 2022-06-13 15:09:18 发布

转载最新推荐文章于 2022-06-13 15:09:18 发布 · 163 阅读

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CC 4.0 BY-SA版权

原文链接：https://my.oschina.net/Tsybius2014/blog/276653

文章标签：

#c/c++

本文介绍了一个使用C++编写的程序，用于解析配置文件config.ini，并根据输入的分类名和属性名获取对应的属性值。程序能够忽略多余空格、处理注释行，并在配置文件中查找指定的组和属性。

1.题目

有文件 config.ini 如下：

[config1]
attribute1 = abc
attribute2 = def
attribute3 = abcde

[config2]
attributex=cat
attributey   =dog
attributez=   mouse

[config3]
#attribute_alpha = alpha
attribute_beta = beta
attribute_gamma = gamma

其中，config1、config2、config3 为分类，每个分类下有若干属性，要求

输入：分类名、属性名（如： config1 attribute1）

输出：属性值（如果是上面的输入，则返回 abc）

要求程序可以忽略每一行中多余的空格，如果一行第一个非空格字符为'#'，则视作注释处理

2.代码

在文件 reader.cpp 中有如下代码

#include <iostream>
#include <fstream>
#include <cstdlib>
#include <string>

using namespace std;

string trim(string s)
{
    if(s.empty())
    {
        return s;
    }
    s.erase(0, s.find_first_not_of(" "));
    s.erase(s.find_last_not_of(" ") + 1);
    return s;
}

int main()
{
    //enter group and  attribute
    cout << "Please Enter Group and Attribute Name: " << endl;
    string sgroup = "", sattr = "";
    cin >> sgroup >> sattr;
    
    //sign if group or attribute be found
    bool isGroupFound = false;
    bool isAttributeFound = false;

    //check for gourps and attributes
    while(sgroup != "#")
    {
        //open file config.ini
        ifstream infile("config.ini", ios::in);
        if(!infile)
        {
            cout << "something error!" << endl;
            exit(1);
        }
        cout << "file opened successfully!" << endl;

        //Initialize the Parameters
        isGroupFound = false;
        isAttributeFound = false;

        cout << "Check for Gourps: "  << sgroup << endl;

        string temp;
        while(getline(infile, temp))
        {
            if(trim(temp) == ("[" + sgroup + "]"))
            {
                cout << "Group Matched!" << endl;
                isGroupFound = true;
                break;
            }
        }
        
        if(!isGroupFound)
        {
            cout << "Group Not Found!" << endl;
        }
        else
        {
            cout << "Check for Attributes: " << sattr << endl;
            while(getline(infile, temp))
            {
                temp = trim(temp);
            
                //commit - continue; the end of group - break;
                if(temp[0] == '#')
                {
                    continue;
                }
                else if(temp[0] == '[')
                {
                    break;
                }
    
                //if attrname is equal to sattr then print attrvalue (word after '=')
                string attrname = "";
                string attrvalue = "";
    
                for(int i = 0; i < temp.length(); i++)
                {
                    if(temp[i] != '=')
                    {
                        attrname += temp[i];
                        continue;
                    }
    
                    if(trim(attrname) == sattr)
                    {
                        cout << "Attribute Matched!" << endl;

                        //read attrvalue
                        i++;
                        while(i < temp.length())
                        {
                            attrvalue += temp[i++];
                        }
                        cout << "\nValue is " << trim(attrvalue) << "\n\n";
                        isAttributeFound = true;
                        break;
                    }
                    else
                    {
                        break;
                    }
                }

                if(isAttributeFound)
                {
                    break;
                }
            }

            if(!isAttributeFound)
            {
                cout << "Attribute Not Found!" << endl;
            }
        }

        infile.close();
        cout << "File Closed." << endl;

        //Input next group and attribute
        cin >> sgroup >> sattr;
    }

    cout << "file closed" << endl;

    return 0;
}

3.makefile文件

在同一目录下有文件makefile，内容如下：

conf_reader: reader.o
    g++ -o conf_reader reader.o
reader.o: reader.cpp
    g++ -c reader.cpp
clean:
    rm -rf *.o conf_reader

4.运行结果

输入 make 命令，生成文件 conf_reader，输入下面的命令启动程序

./conf_reader

启动程序后的一个运行示例如下

END

转载于:https://my.oschina.net/Tsybius2014/blog/276653