在C ++中查找和修改文本文件

Posted 2021-03-29

我想从文件中找到特定的id并修改内容。 这是我想要的原始代码。

// test.txt

id_1
arfan
haider

id_2
saleem
haider

id_3
someone
otherone

C ++代码：

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

using namesapce std;

int main(){
     istream readFile("test.txt");
     string readout;
     string search;
     string Fname;
     string Lname;

     cout<<"Enter id which you want Modify";
     cin>>search;

     while(getline(readFile,readout)){
        if(readout == search){
           /*
                id remain same (does not change)
                But First name and Last name replace with
                user Fname and Lname
           */
            cout<<"Enter new First name";
                 cin>>Fname;
            cout<<"Enter Last name";
                 cin>>Lname;  
        }
    }
}  

假设： 用户搜索ID * id_2 *。之后，用户输入名字和姓氏Shafiq和Ahmed。 运行此代码后，test.txt文件必须修改如下记录：

...............
...............

id_2
Shafiq
Ahmad

.................
.................

只有id_2记录更改重映射文件将是相同的。 更新：

#include <iostream>
#include <string.h>
#include <fstream>

using namespace std;

int main()
{
ofstream outFile("temp.txt");
ifstream readFile("test.txt");

string readLine;
string search;
string firstName;
string lastName;

cout<<"Enter The Id :: ";
cin>>search;

while(getline(readFile,readLine))
{
    if(readLine == search)
    {
        outFile<<readLine;
        outFile<<endl;

        cout<<"Enter New First Name :: ";
        cin>>firstName;
        cout<<"Enter New Last Name :: ";
        cin>>lastName;

        outFile<<firstName<<endl;
        outFile<<lastName<<endl;
    }else{
        outFile<<readLine<<endl;
    }
}
}

它还包含temp.txt文件中的前一个名字和姓氏。

答案

找到特定的ID并写入新的名字和姓氏后，您需要跳过以下两行。此代码有效：

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

using namespace std;
void skipLines(ifstream& stream, int nLines)
{
    string dummyLine;
    for(int i = 0; i < nLines; ++i)
        getline(stream, dummyLine);
}

int main()
{
    ofstream outFile("temp.txt");
    ifstream readFile("test.txt");

    string readLine;
    string search;
    string firstName;
    string lastName;

    cout<<"Enter The Id :: ";
    cin>>search;

    while(getline(readFile,readLine))
    {
        if(readLine == search)
        {
            outFile<<readLine;
            outFile<<endl;

            cout<<"Enter New First Name :: ";
            cin>>firstName;
            cout<<"Enter New Last Name :: ";
            cin>>lastName;

            outFile<<firstName<<endl;
            outFile<<lastName<<endl;
            skipLines(readFile, 2);
        }
        else
        {
            outFile<<readLine<<endl;
        }
    }
}