C++不插入第一行數據到輸出文件

Question

我對C++相對來說比較新，並且一直在通過獲取數據文件並讀取它，然後將這些數據與其中的一些數據進行數學運算，然後將其全部導出到輸出文件。然而，我的問題是每次運行它跳過寫入輸出文件的第一行。

我的數據文件是：

Jon Doe 15 7.25 
Nick Delgado 8 7.25 
Jo Barnes 4 7.25 
Harold Griffith 45 11.00 
Linda Holmes 30 10.00 

我的輸出是這樣的：

Nick Delgado 8 7.25 58 0 58 
Jo Barnes 4 7.25 29 0 29 
Harold Griffith 45 11 522.5 146.3 376.2 
Linda Holmes 30 10 300 84 216 

它完全跳過寫出關於喬恩Doe的任何信息。那就是：

Jon Doe 15 7.25 108.75 0 108.75 

我試過多種不同的想法，問我的朋友，總體來說，我感到非常沮喪。

我想這個問題的代碼是在這裏的某個地方：

if (!dataOutFile.is_open()) { 
     cout << "Couldn't open file"; 
    } 
    else { 
     dataOutFile << firstName << " " << lastName << " " << hoursWorked << " " << payRate << " " << grossPay << " " << withHolding << " " << takeHomePay << endl; 
     cout << "What was wrote to file: \n" << firstName << " " << lastName << " " << hoursWorked << " " << payRate << " " << grossPay << " " << withHolding << " " << takeHomePay << endl; 
    } 

因爲我的輸出窗口如下所示：

那麼，告訴我的是，它越來越向代碼寫入文件的位置，因爲它正在寫入第一個條目之後的其他四個條目。但是，根據輸出窗口，它正在向文件寫入它應該的信息 - 但由於某種原因，它不是。我使用append命令，所以它不應該覆蓋任何東西，根據輸出文件，它不是，但可能是第一行。

沒有錯誤或警告，我的調試日誌沒有錯誤。請幫助我，任何幫助表示讚賞。我也意識到代碼有點亂，我需要把它分解成更多的功能，但我只是想讓這個工作，然後我可以清理它。

我的程序處理所有這些的完整代碼如下，以防萬一需要看到它。

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

using namespace std; 

// Global Variables 
string fileName; 
double totalGrossPay = 0; 
double totalWithHolding = 0; 
double totalTakeHomePay = 0; 
double withHoldingLimit = 200; 
double withHoldingRate = .28; 
double overtimeRate = 1.5; 

// Initialize Functions 
void readFile(); 

int main() { 
    cout << "What is the name of your file?" << endl; 
    getline(cin, fileName); 
    readFile(); 
} 

void readFile() { 
    // Variables 
    string firstName; 
    string lastName; 
    double hoursWorked; 
    double payRate; 
    double grossPay; 
    double withHolding; 
    double takeHomePay; 
    double overtime; 
    string dataOutFileName = "Salary.out"; 

    // Intialize and Open Input File 
    ifstream file; 
    file.open(fileName); 
    // Initialize Output File 
    ofstream dataOutFile(dataOutFileName); 

    // Check to see if file failed to open 
    if (!file.is_open()) return; 

    // Define variables needed in the while loop. 
    string word; 
    int i = 1; 

    // Actually reads through the file and prints out what the file has. 
    while (i != 0) { 
     // Pull up the next word in the word file 
     file >> word; 
     // Firstname 
     if (((i - 1) % 4) == 0) { 
      firstName = word; 
      cout << "First name: " << firstName << "\n"; 
     } 
     // Last name 
     else if (((i - 1) % 4) == 1) { 
      lastName = word; 
      cout << "Last name: " << lastName << "\n"; 
     } 
     // Hours Worked 
     else if (((i - 1) % 4) == 2) { 
      hoursWorked = atof(word.c_str()); 
      cout << "Hours Worked: " << hoursWorked << "\n"; 
     } 
     // Pay Rate 
     else if (((i - 1) % 4) == 3) { 
      payRate = atof(word.c_str()); 
      cout << "Pay Rate: " << payRate << "\n"; 
     } 
     // Add 1 to i 
     i++; 
     // If i-1 divides into 4 with no remainder, move to new line 
     // Also since we now have all four variables filled in we can do our math 
     if (i > 3 && ((i - 1) % 4) == 0) { 
      // Gross Pay 
      if (hoursWorked > 40) { 
       overtime = hoursWorked - 40; 
      } 
      else { 
       overtime = 0; 
      } 
      if (overtime != 0) { 
       grossPay = (40 * payRate) + (overtime * (payRate * overtimeRate)); 
      } 
      else { 
       grossPay = hoursWorked * payRate; 
      } 
      // Withholding 
      if (grossPay > withHoldingLimit) { 
       withHolding = grossPay * withHoldingRate; 
      } 
      else { 
       withHolding = 0; 
      } 
      // Take Home pay 
      takeHomePay = grossPay - withHolding; 
      // Add to totals 
      totalGrossPay += grossPay; 
      totalWithHolding += withHolding; 
      totalTakeHomePay += takeHomePay; 
      // Write to file, and print the line so we know it worked! 
      dataOutFile.open(dataOutFileName, fstream::app); 
      // Check it if is open 
      if (!dataOutFile.is_open()) { 
       cout << "Couldn't open file"; 
      } 
      else { 
       dataOutFile << firstName << " " << lastName << " " << hoursWorked << " " << payRate << " " << grossPay << " " << withHolding << " " << takeHomePay << endl; 
       cout << "What was wrote to file: \n" << firstName << " " << lastName << " " << hoursWorked << " " << payRate << " " << grossPay << " " << withHolding << " " << takeHomePay << endl; 
      } 
      dataOutFile.close(); 
      // move to new line 
      cout << "\n"; 
     } 
     // Check to see if were at the end of the file, if so end while. 
     if (file.eof()) { 
      i = 0; 
     } 
    } 
    file.close(); 
} 

Answer 1

基於i的狀態機太複雜，完全不需要。不要修理它，把它扔掉。

如果您需要閱讀四件事，請一次閱讀四件事。在一段時間內進行。

ifstream file(filename); 
ofstream dataOutFile(dataOutFileName); 

while (file >> firstName >> lastName >> hoursWorked >> payRate) 
{ 
     // you have all four pieces of data 
     // calculate and print what you need here 
} 

不要叫close()或檢查eof()循環內。