我正在为我的主题做一个作业，在作业中，每个学生都需要创建一个简单的C ++程序。这里的问题是，当我没有为变量赋值时，会发生编译错误。但是，当我指定默认值（在这种情况下，值= 0）时，该值将始终为0.
我的问题是，有没有办法解决这个问题而没有遇到编译错误？
如果有类似的问题，请问您也可以包含解决问题的链接吗？非常感谢你！
[编辑＃1 ：对于那些想知道为什么代码“混乱”的人，我只使用简单的命令而没有使用面向对象的组件，if / else语句等。项目创建的是意思是由“简单代码”组成。]
[编辑＃2 ：这是我拍摄的输出显示： http://i.imgur.com/4csk1Rz.png
总折扣费用部分应显示数字而非默认值0]
（Microsoft Visual Studio Pro 2013; C ++）
预期输出显示： http://i.imgur.com/jOJvymV.png
#include "stdafx.h"
#include <iostream>
#include <iomanip>
#include <cmath>
using namespace std;
int main()
{
/* Declare variables */
int qtyVehicleCar, qtyVehicleTaxi, qtyVehicleTruck; // User input
double feeOriginalCar, feeTotalOriginalCar, rateDiscountCar, feeTotalDiscountedCar, feeTotalAfterDiscountedCar; // variables for vehicle Car
double feeOriginalTaxi, feeTotalOriginalTaxi, rateDiscountTaxi, feeTotalDiscountedTaxi, feeTotalAfterDiscountedTaxi; // variables for vehicle Taxi
double feeOriginalTruck, feeTotalOriginalTruck, rateDiscountTruck, feeTotalDiscountedTruck, feeTotalAfterDiscountedTruck; // variables for vehicle Truck
double feeRepTotalOriginalFee, feeRepTotalDiscountedFee, feeRepTotalAfterDiscounted; // Generate final output
cout << "=====================================\n";
cout << "=====================================\n";
cout << "====== Malaysia Highway Company =====\n";
cout << "=====================================\n";
cout << "=====================================\n";
cout << endl;
cout << "Enter quantity of the vehicles on 1st January 2014: " << endl;
cout << "Car\t\t:\t";
cin >> qtyVehicleCar;
cout << "Taxi\t\t:\t";
cin >> qtyVehicleTaxi;
cout << "Truck\t\t:\t";
cin >> qtyVehicleTruck;
/* Lay out the Report table */
cout << endl << endl << endl;
cout << "Report\n";
cout << "--------\n";
cout << endl;
/* ============================== */
/* Declaration prior to process */
/* ============================== */
/* The problematic part
feeTotalDiscountedCar = 0;
feeTotalDiscountedTaxi = 0;
feeTotalDiscountedTaxi = 0;
*/
// Prices
feeOriginalCar = 2.00;
feeOriginalTaxi = 1.00;
feeOriginalTruck = 3.50;
feeTotalOriginalCar = feeOriginalCar * qtyVehicleCar;
feeTotalOriginalTaxi = feeOriginalTaxi * qtyVehicleTaxi;
feeTotalOriginalTruck = feeOriginalTruck * qtyVehicleTruck;
// In percentage
rateDiscountCar = 2;
rateDiscountTaxi = 10;
rateDiscountTruck = 15;
feeTotalAfterDiscountedCar = (rateDiscountCar/100) * feeTotalOriginalCar;
feeTotalAfterDiscountedTaxi = (rateDiscountTaxi/100) * feeTotalOriginalTaxi;
feeTotalAfterDiscountedTruck = (rateDiscountTruck/100) * feeTotalOriginalTruck;
// Final total - to be displayed
feeTotalAfterDiscountedCar = feeTotalOriginalCar - feeTotalAfterDiscountedCar;
feeTotalAfterDiscountedTaxi = feeTotalOriginalTaxi - feeTotalAfterDiscountedTaxi;
feeTotalOriginalTruck = feeTotalOriginalTruck - feeTotalAfterDiscountedTruck;
feeRepTotalOriginalFee = feeTotalOriginalCar + feeTotalOriginalTaxi + feeTotalOriginalTruck;
feeRepTotalDiscountedFee = feeTotalDiscountedCar + feeTotalAfterDiscountedTaxi + feeTotalAfterDiscountedTruck;
feeRepTotalAfterDiscounted = feeRepTotalOriginalFee - feeRepTotalDiscountedFee;
/* ================= */
/* Declaration END */
/* ================= */
/* Gives the following variables a default value, they will be modified later by the program */
feeTotalAfterDiscountedTruck = 0;
feeTotalDiscountedTruck = 0;
/* Processes */
cout << "Item\t\t\t\t" << "Car\t" << "Taxi\t" << "Truck\t" << endl;
cout << "------------------------------------------------------\n";
cout << "Original fee\t\t\t" << "RM " << feeOriginalCar << "\t" << "RM " << feeOriginalTaxi << "\t" << "RM " << feeOriginalTruck << endl;
cout << "Quantity\t\t\t" << qtyVehicleCar << "\t" << qtyVehicleTaxi << "\t" << qtyVehicleTruck << endl;
cout << "Total original fee\t\t" << "RM " << feeOriginalCar << "\t" << "RM " << feeOriginalTaxi << "\t" << "RM " << feeOriginalTruck << endl;
cout << "Discount rate\t\t\t" << rateDiscountCar << "%\t" << rateDiscountTaxi << "%\t" << rateDiscountTruck << "%\t" << endl;
cout << "Total discounted fee\t\t" << "RM " << feeTotalDiscountedCar << "\t" << "RM " << feeTotalDiscountedTaxi << "\t" << "RM " << feeTotalDiscountedTruck << endl;
cout << "Total after discounted fee\t" << "RM " << feeTotalAfterDiscountedCar << "\t" << "RM " << feeTotalAfterDiscountedTaxi << "\t" << "RM " << feeTotalAfterDiscountedTruck << endl;
cout << endl;
/* Displays output */
cout << "Total original fee\t\t:\t" << "RM " << feeRepTotalOriginalFee << endl;
cout << "Total discounted fee\t\t:\t" << "RM " << feeRepTotalDiscountedFee << endl;
cout << "Total after discounted fee\t:\t" << "RM " << feeRepTotalAfterDiscounted << endl;
cout << endl << endl;
/* Displays end line */
cout << "------------------- End of Program -------------------" << endl;
system("PAUSE");
return 0;
}
答案 0 :(得分：2)
未初始化的变量警告可能意味着（1）您忘记初始化某些内容或（2）您认为您已将其初始化但未进行初始化。在我看来，这是第二个问题。您的变量名称已混淆。
例如，
feeTotalAfterDiscountedCar = (rateDiscountCar/100) * feeTotalOriginalCar;
feeTotalAfterDiscountedTaxi = (rateDiscountTaxi/100) * feeTotalOriginalTaxi;
feeTotalAfterDiscountedTruck = (rateDiscountTruck/100) * feeTotalOriginalTruck;
这些应该是折扣金额，不是吗？那么为什么要将它们存储到feeTotalAfterDiscountedSomething而不是feeTotalDiscountedSomething？
类似地，
feeTotalAfterDiscountedCar = feeTotalOriginalCar - feeTotalAfterDiscountedCar;
feeTotalAfterDiscountedTaxi = feeTotalOriginalTaxi - feeTotalAfterDiscountedTaxi;
feeTotalOriginalTruck = feeTotalOriginalTruck - feeTotalAfterDiscountedTruck;
为什么第三个将结果存储到feeTotalOriginalTruck而不是feeTotalAfterDiscountedTruck？ （另请注意，如果你解决了上面的第一个问题，减法的rhs也需要改变）。
此外，
feeRepTotalDiscountedFee = feeTotalDiscountedCar + feeTotalAfterDiscountedTaxi + feeTotalAfterDiscountedTruck;
类似的问题。我相信，这些应该是feeTotalDiscountedSomething而不是feeTotalAfterDiscountedSomething。
答案 1 :(得分：0)
编译器正确地抱怨feeTotalDiscountedCar和feeTotalDiscountedTaxi未初始化。你需要在某处初始化它们。也许你希望用户在这样的地方输入它们：
cout << "Discount Fee Total Taxi:";
cin >> feeTotalDiscountedTaxi;
cout << "Discount Fee Total Car:";
cin >> feeTotalDiscountedCar;
答案 2 :(得分：0)
为什么要在打印之前将它们设置为零？
feeTotalAfterDiscountedTruck = 0;
feeTotalDiscountedTruck = 0;
它将显示错误，因为您尝试使用该变量而不进行初始化。