Question

我昨天发布了这个程序（如果您昨天没有看到它，我在下面重新发布了一个基本摘要），你们告诉我我的布尔逻辑有什么问题，所以一切都按我的意愿运行to，但如果我使用while（inFile）或while（！inFile.eof（））等等，我正在处理最后一行两次。因此，我想使用stringstream，以便我可以处理输入逐行。

由于输入数据不仅仅是一种数据类型（它是int，int，char，char，float），我还是按照以下方式使用stringstream（如下面的代码所示）：

while (getline(inFile, line)){

istringstream ss(line);

while(ss >> numAdults >> numChildren >> mealType >> dayType >> depositAmount){

这些是我正在尝试在输入文件中以正确顺序读取的变量。会发生的是，我的billing_statement文本文件中有4行输出，error_report文本文件中有3行输出（输入文本文件中总共有13行）。似乎有些线路可能会合并在一起。感谢这里的帮助。

感谢。

输入文件：

10 0 S Y 100.00

27 3 D Y 57.50

125 17 D N 0.00

4 0 S N 25.00

0 25 S Y 23.75

250 43 D N 500.00

0 0 D N 0.0

10 0 R Y 10.00

17 3 D R 15.00

5 0 D Y 275.00

-3 10 D Y 20.00

14 -1 S N 30.00

20 3 D Y -10.00

这是昨天我的帖子的链接，它解释了我的程序，虽然我的具体问题不应该需要...

C++: Mock Catering Company Billing Program - Not able to ouput bad data to error file

#include <iostream>
#include <fstream>
#include <iomanip>
#include <sstream>
#include <string>


using namespace std;

void getData(int &, int &, char &, char &, float &);
void checkValid(int &, int &, char &, char &, float &, bool &);
void calcData(int, int, char, char, float, float &, float &, float &, float &);
void sendData(int, int, char, char, float, float &, float &, float &, float &);

ifstream inFile;
ofstream outFile("Billing_Statement.txt");
ofstream error_Report("Error_Report.txt");

//Declare the tax rate and weekend surcharge as constants.

const float taxRate = 0.18;
const float weekendSurcharge = .07;

int main()
{

bool valid = true;
float mealCost;
float totalTax;
float totalSurcharge;
float discountAmount;
int numAdults;
int numChildren;
char mealType;
char dayType;
float depositAmount;
string line;

cout << "\nThis program will calculate data for a catering company " << endl;

outFile << " Adults " << "Children  " << "Meal " << " Weekend " << setw(9) << "Deposit "
<< setw(6) << "Tax" << setw(11) << "Surcharge" << setw(10) << "Discount" << setw(12) << 
"Meal Cost" << endl;
error_Report << " Adults " << "Children  " << "Meal " << " Weekend " << setw(9) << 
"Deposit " << endl;

inFile.open("file.txt");

if (!inFile) {
cout << "\nError: File could not be opened. ";
//exit(1);
}

while (getline(inFile, line)){

istringstream ss(line);

while(ss >> numAdults >> numChildren >> mealType >> dayType >> depositAmount){
getData(numAdults, numChildren, mealType, dayType, depositAmount);
checkValid(numAdults, numChildren, mealType, dayType, depositAmount, valid);

if (valid == true)
{
    calcData(numAdults, numChildren, mealType, dayType, depositAmount, totalTax,
 totalSurcharge, discountAmount, mealCost);
    sendData(numAdults, numChildren, mealType, dayType, depositAmount, mealCost, 
totalTax, totalSurcharge, discountAmount);
}}
}

cout << "\nA copy of this has created for your convenience in the file, 
Billing_Statement.txt" << endl;

inFile.close();
outFile.close();
error_Report.close();

return 0;

}

void getData(int & numAdults, int & numChildren, char & mealType, char & dayType, float
& depositAmount)
{
inFile >> numAdults >> numChildren >> mealType >> dayType >> depositAmount;
}

void checkValid(int & numAdults, int & numChildren, char & mealType, char & dayType, 
float & depositAmount, bool & valid)
{

if (numAdults < 0 || numChildren < 0)
valid = false;
else if (!(mealType == 'D' || mealType == 'S'))
valid = false;
else if (!(dayType == 'Y' || dayType == 'N'))
valid = false;
else if (depositAmount < 0)
valid = false;

else
valid = true;

if (valid == false) {

error_Report << setw(7) << numAdults << setw(9) << numChildren << setw(6) << 
mealType << setw(9) << dayType << setw(9) << right << depositAmount << setw(8) << endl;
}
}

void calcData(int numAdults, int numChildren, char mealType, char dayType, float  
depositAmount, float & totalTax, float & totalSurcharge, float & discountAmount, float & 
mealCost)
{

if (mealType == 'S') {

mealCost = ((numAdults * 21.75) + (numChildren * (21.75 * .60)));
totalTax = mealCost * taxRate;
mealCost += taxRate;

if (dayType == 'Y') {
    totalSurcharge = mealCost * weekendSurcharge;
    mealCost += totalSurcharge;
}}

else {

mealCost = ((numAdults * 25.80) + (numChildren * (25.80 * .60)));
totalTax = mealCost * taxRate;
mealCost += taxRate;

if (dayType == 'Y') {
    totalSurcharge = mealCost * weekendSurcharge;
    mealCost += totalSurcharge;
    }
}

if (mealCost < 100) {

discountAmount = .015 * mealCost;
mealCost -= discountAmount;
}

else if (mealCost >= 100 && mealCost < 400) {

discountAmount = .025 * mealCost;
mealCost -= discountAmount;
}

else if (mealCost >= 400) {

discountAmount = .035 * mealCost;
mealCost -= discountAmount;
}
}

void sendData(int numAdults, int numChildren, char mealType, char dayType, float
depositAmount, float &mealCost, float &totalTax, float &totalSurcharge, float 
&discountAmount)
{
outFile << fixed << showpoint << setprecision(2);
outFile << setw(7) << numAdults << setw(9) << numChildren << setw(6) << mealType <<
setw(9) << dayType << setw(9) << right << depositAmount << setw(8) << totalTax << 
setw(10) << totalSurcharge << setw(10) << right << discountAmount << setw(12) << right 
<< mealCost << endl;
}

Answer 1

问题是，您的getData()函数正在从inFile读取输入：std::getline()读取一行，getData()读取下一行。似乎getData()旨在读取嵌套while中实际读取的数据。就像现在一样，getData()实际上是有害的。我会将代码更改为

不使用嵌套的while - 循环，而是使用if语句。
如果无法读取该行，即在if的{{1}} - 分支中打印。
删除else。
缩进代码以反映其结构。
当然，我wouldn't use std::endl但getData()。
不需要'\n'个文件，因为无论如何，各个流的析构函数都会这样做（只需要使用close()就可以处理错误了。）

C ++：我在这里使用Stringstream有什么问题？

1 个答案: