Question

我在程序中遇到问题，我想删除所有内容并重新输入，但是我的文本文件先前的内容不会删除。我想知道如何解决。

我的文本文件格式：

jam：A7D579BA76398070EAE654C30FF153A4C273272A：9BB8F747A1C0DEA66C6FAF43391FEEAB：7F273F63581093D2：08102018： kelly：7C222FB2927D828AF22F592134E8932480637C0D：06FE625E35A95669B866B914ABE818DE：7F273F63581093D2：08102018：

我的代码：

#include <iostream>
#include <cstdlib>
#include <cstring>
#include <string>
#include <sstream>
#include <ctime>
#include <unistd.h>
#include <pthread.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
using namespace std;


string SHA_1(const string& input_data)
{
    string digest;
    SHA1 hash;

    StringSource s(input_data, true, new HashFilter(hash, new HexEncoder(new StringSink(digest))));

    return digest;
}

void outfile (string filename, string u, string p , string k, string iv, string d)
{

    ofstream outfile, outfile_2;
    outfile_2.open ("Account.txt", ios::out | ios::app);
    outfile_2 << u + ":" + p + ":" + ":" + k + ":" + iv + ":" + d + ":";
    outfile_2.close();
}
int main()
{

    ifstream infile_Account;
    infile_Account.open("Account.txt", ios::in);
    string UserAccount;

    string KEY_2;
    string IV_2;

    string Username = "kelly";
    string Password = "12345678";
    string Hashed_Password = SHA_1(Password);
    int i = 0;
    int j = 0;

    if (!infile_Account)
    {
        cout << "File " << endl;
        return 0;
    }
    while(infile_Account >> UserAccount)
    {
        //cout << UserAccount << endl;
        i++;
    }
    infile_Account.close();
    string u, p , k , iv ,d;

    cout << i << endl;

    ifstream infile_Account_2;
    infile_Account_2.open("Account.txt", ios::in);
    ofstream outfile1;

    for (int j =0; j<i ; j++)
    {
        getline(infile_Account_2,u, ':');
        getline(infile_Account_2,p, ':');
        getline(infile_Account_2,k, ':');
        getline(infile_Account_2,iv, ':');
        getline(infile_Account_2,d, ':');

        /*cout << u << endl;
        cout << p << endl;
        cout << k << endl;
        cout << iv << endl;
        cout << d << endl;*/

        if (u == Username && p == Hashed_Password )
        {
            p = "78965478";
        }

        outfile("Account.txt",u,p,k,iv,d);
    }
}

执行程序后文件的结果：

kelly:7C222FB2927D828AF22F592134E8932480637C0D:06FE625E35A95669B866B914ABE818DE:7F273F63581093D2:08102018:
jam:A7D579BA76398070EAE654C30FF153A4C273272A:9BB8F747A1C0DEA66C6FAF43391FEEAB:7F273F63581093D2:08102018:
kelly:78965478:06FE625E35A95669B866B914ABE818DE:7F273F63581093D2:08102018:
jam:A7D579BA76398070EAE654C30FF153A4C273272A:9BB8F747A1C0DEA66C6FAF43391FEEAB:7F273F63581093D2:08102018:

Answer 1

您正在使用ios::app打开文件。因此，您要追加数据。 Juste删除标志...并阅读文档。

如何在输入新内容之前删除文件中的所有内容C ++

1 个答案: