我尝试在 C++ 源文件中使用文件处理。 该文件的目的是读取名为 ClientList.txt 的 .txt 文件 并写下内容 到一个名为 ClientListv2.txt 的新文件，同时修改预先存在的数据。
George A Harrison 713-555-1234 gaharrison@gmail.com 250 N Main Street, Baytown, TX
James K Smith 713-555-1235 jksmith@gmail.com 100 Cactus St, Baytown, TX
Alma P Sanchez 713-554-1237 apsanchez@gmail.com 312 Luella Blvd, Pasadena, TX
Samantha J Jones 713-554-1238 sjjones@gmail.com 125 Purdue Ln, Pasadena, TX
Paula Mary Henry 713-553-1239 pmhenry@gmail.com 412 Colorado Ave, League City, TX
Henry B Albertson 713-553-2345 hbalbertson@gmail.com 724 Perkins Ave, League City, TX
Samuel * Harrison 713-552-2346 sharrison@gmail.com 200 Wesley Ln, Deer Park, TX
Peter N Smith 713-552-2347 pnsmith@gmail.com 157 Briarwood Ct, Deer Park, TX
James Edward Bennett 713-551-2348 jebennett@gmail.com 330 S 6th St, La Porte, TX
Javier D Rodriquez 713-551-2349 jdrodriquez@gmail.com 245 Parkcrest Dr, La Porte, TX
任务是创建一个名为 ClientListv2.txt 的重复文件，其中包含所有预先存在的 信息，带有两条附加记录，以及任何一条线路的电话号码和地址的更改。 （记录）
//我从包含头文件开始：
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
int main()
{
//reading the file
fstream file;
file.open("ClientList.txt", ios::in | ios::out);
if (!file.is_open())
{
cout << "File does not exist" << endl;
exit(0);
}
char FirstName[10];
char MiddleName[10];
char LastName[15];
char Phone[15]; //one extra char for '\0' (string terminal char)
char Email[31];
char Address_num[8];
char Address_street[25];
char Town[25];
char State[8];
while (file.good())
{
file.getline(FirstName, 9, ' ');
file.getline(MiddleName, 9, ' ');
file.getline(LastName, 14, ' ');
file >> ws;
file.getline(Phone, 14, ' ');
file >> ws;
file.getline(Email, 30, ' ');
file >> ws;
file.getline(Address_num, 7, ' ');
file >> ws;
file.getline(Address_street, 24, ',');
file >> ws;
file.getline(Town, 24, ',');
file >> ws;
file.getline(State, 7);
file.clear();
file >> ws;
cout << FirstName << " " << MiddleName << " " << LastName << " " << Phone << " " << Email << " " << Address_num << " " << Address_street << " " << Town << " " << State << endl;
}
//To modify one phone and one street address of any single record(line), I used this approach...
fstream new_file;
new_file.open("ClientListv2.txt", ios::out | ios::in);
//file.clear();
file.seekg(0, ios::beg);
file.seekp(0, ios::beg);
char c;
while (file.good())
{
file.get(c);
new_file << c;
}
//declaring a string to take a whole line
string line;
int line_num;
//go to the beginning of the new_file
new_file.seekg(0, ios::beg);
new_file.seekp(0, ios::beg);
cout << "Enter Line No to Edit Phone Number (First Line is 1): " << endl;
cin >> line_num;
for (int i = 1; i < line_num; i++)
{
getline(new_file, line);
}
new_file.seekp(22, ios::cur);
new_file << "888-888-8888";
cout << new_file.tellp() << endl;
cout << new_file.tellg() << endl; //34
cout << new_file.tellp() << endl;
new_file.seekg(0, ios::beg); //moving the flag pointers to the beginning of the file
new_file.seekp(0, ios::beg);
cout << "Enter Line No to Edit Street Address (First Line is 1): " << endl;
cin >> line_num;
for (int i = 1; i < line_num; i++)
{
getline(new_file, line);
}
//65 street address
new_file.seekp(64, ios::cur);
new_file << "B Tane Stripe"; //any address you want to add
cout << new_file.tellg() << endl; //78
cout << new_file.tellp() << endl;
//move the file markers to the end of the file
new_file.seekg(0, ios::end);
new_file.seekp(0, ios::end);
cout << "\t\t\tUpdating Client List Text File\t\t\t" << endl;
//two add two addional clients
cout << "\nEnter the first addional record:\n";
cout << "Enter the FirstName" << endl;
cout << "Enter the MiddleName" << endl;
cout << "Enter the LastName" << endl;
cout << "Enter the Phone" << endl;
cout << "Enter the Email" << endl;
cout << "Enter the Address_num" << endl;
cout << "Enter the Address_street" << endl;
cout << "Enter the Town" << endl;
cout << "Enter the State" << endl;
cin >> FirstName;
cin >> MiddleName;
cin >> LastName;
cin >> Phone;
cin >> Email;
cin >> Address_num;
cin.ignore();
cin.getline(Address_street, 24);
cin.getline(Town, 24);
cin >> State;
new_file.clear();
new_file << "\n" << FirstName << " " << MiddleName << " " << LastName << " " << Phone << " " << Email << " " << Address_num << " " << Address_street << " " << Town << " " << State << endl;
cout << "\nEnter the second addional record:\n";
cout << "Enter the FirstName" << endl;
cout << "Enter the MiddleName" << endl;
cout << "Enter the LastName" << endl;
cout << "Enter the Phone" << endl;
cout << "Enter the Email" << endl;
cout << "Enter the Address" << endl;
cout << "Enter the Town" << endl;
cout << "Enter the State" << endl;
cin >> FirstName;
cin >> MiddleName;
cin >> LastName;
cin >> Phone;
cin >> Email;
cin >> Address_num;
cin.ignore();
cin.getline(Address_street, 24);
cin.getline(Town, 24);
cin >> State;
new_file << FirstName << " " << MiddleName << " " << LastName << " " << Phone << " " << Email << " " << Address_num << " " << Address_street << " " << Town << " " << State << endl;
file.close();
new_file.close();
return 0;
}
在完成所有这些之后，我首先注意到，我的代码仅在我手动创建 ClientListv2.txt 时才有效。 当前工作目录。如果没有，代码本身不会生成新的 .txt 文件。其次，使用 TDM GCC 4.9.2 编译器，我得到了非常奇怪的基于模式的 跨多行检查我的电话号码和地址时的输出序列。 看起来，代码覆盖了一些旧文本，有时它没有覆盖。
出于某种原因，当我尝试在 Visual Studio（Microsoft C++ 编译器 MSVC）上编译和运行它时，我得到了正确的结果。 为什么 TDM GCC 4.9.2 会这样？ 我的机器运行 Windows 10 64 位。我想 '\r\n' 可能对这个奇怪的输出负责。谁知道？
我使用以下虚拟文本来输入另外两行的值：
Sam
Billy
Jhons
299-292-9292
sambilly@gmail.com
39
2nd Street
Ventnor
NJ