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我是C++的新手，我想了解如何通过多个函数传递变量。我明白你可以使用全局变量或参数传递。不理解通过函数传递的C++参数
在我的代码中，我定义了两个函数，在main函数之后。我用原型设定了它。我在CodeBlocks中收到的错误是.error: 'studentFees' was not declared in this scope。这是有道理的，因为我没有执行123和124行中的任何内容。但我不太清楚如何。我也没有很好地对原型进行适当的实施。
有人可以帮我解决这个问题吗？
#include <iostream>
#include <iomanip>
#include <cstdlib>
#include <fstream>
#include <string>
using namespace std;
void undergradBill(
double finalBill = 0;
double studentTuition,
double studentFees,
double studentID,
string studentLevel,
string studentBio,
string studentRes,
string studentLife,
string studentCredit
);
void gradBill(
double finalBill = 0;
double studentTuition,
double studentFees,
double studentID,
string studentLevel,
string studentBio,
string studentRes,
string studentLife,
string studentCredit
);
int main()
{
double finalBill = 0;
double studentTuition = 0;
double studentFees = 0;
double studentID = 0;
string studentLevel = "";
string studentBio = "";
string studentRes = "";
string studentLife = "";
string studentCredit = "";
cout << "Welcome College Student!" << endl;
cout << "This program is designed to assist you in calculating your college tuition per semester." << endl;
cout << endl;
cout << "Please provide the following information:" << endl;
cout << " -Student ID" << endl;
cout << " -Graduate/Undergraduate" << endl;
cout << " -Residency" << endl;
cout << " -Major" << endl;
cout << " -Full Time/Part Time" << endl;
cout << " -Credits taken this semester" << endl;
cout << endl;
system("PAUSE");
system("CLS");
cout << "Please enter your student ID." << endl;
cout << "Student ID: ";
cin >> studentID;
while(cin.fail()) {
cout << "Error: please enter a valid entry." << endl;
cin.clear();
cin.ignore(256,'\n');
cout << "Student ID :";
cin >> studentID;
}
cout << endl;
cout << "Are you a graduate or undergraduate student?" << endl;
cout << "(G/U) :";
cin.get();
getline(cin, studentLevel);
while(studentLevel != "g" && studentLevel != "G" && studentLevel != "u" && studentLevel != "U") {
cout << "Error: please enter a valid entry." << endl;
cout << "(G/U) :";
getline(cin, studentLevel);
}
if(studentLevel == "g" || studentLevel == "G") {
cout << endl;
cout << "Are you apart of the biology program?" << endl;
cout << "(Y/N) :";
getline(cin, studentBio);
while(studentBio != "y" && studentBio != "Y" && studentBio != "n" && studentBio != "N") {
cout << "Error: please enter a valid entry." << endl;
cout << "(Y/N) :";
getline(cin, studentBio);
}
}
cout << endl;
cout << "Are you a resident or New York State?" << endl;
cout << "(Y/N) :";
getline(cin, studentRes);
while(studentRes != "y" && studentRes != "Y" && studentRes != "n" && studentRes != "N") {
cout << "Error: please enter a valid entry" << endl;
cout << "(Y/N) :";
getline(cin, studentRes);
}
cout << endl;
cout << "Are you a full time student or a part time student?" << endl;
cout << "(F/P) :";
getline(cin, studentLife);
while(studentLife != "f" && studentLife != "F" && studentLife != "p" && studentLife != "P") {
cout << "Error: please enter a valid entry." << endl;
cout << "(F/P) :";
getline(cin, studentLife);
}
if (studentLife == "p" || studentLife == "P") {
cout << endl;
cout << "How many credit hours are you taking this semester?" << endl;
cout << "Credit Hours :";
cin >> studentCredit;
while(cin.fail()) {
cout << "Error: please enter a valid entry." << endl;
cin.clear();
cin.ignore(256,'\n');
cout << "Credit Hours :";
cin >> studentCredit;
}
}
if(studentLevel == "u" || studentLevel == "U" || studentLife == "p" || studentLife == "P") {undergradBill();}
else {gradBill();}
system("CLS");
finalBill = studentTuition + studentFees;
cout << "Student Account: " << studentID << endl;
cout << "Billing Total: " << finalBill << endl;
}
void undergradBill() {
if(studentLife == "f" || studentLife == "F") {
if(studentRes == "y" && studentRes == "Y") {
studentTuition = 3085.00;
studentFees = 588.50;
}
else {
studentTuition = 7910.00;
studentFees = 588.50;
}
}
else {
if(studentRes == "y" && studentRes == "Y") {
studentTuition = 257.00;
studentFees = studentCredit * 48.95;
}
else {
studentTuition = 659.00;
studentFees = studentCredit * 48.95;
}
}
}
void gradBill() {
if(studentBio == "y" || studentBio == "Y") {
if(studentLife == "f" || studentLife == "F") {
if(studentRes == "y" && studentRes == "Y") {
studentTuition = 5185.00;
studentFees = 342.14 + 900.00;
}
else {
studentTuition = 10095.00;
studentFees = 342.14 + 900.00;
}
}
else {
if(studentRes == "y" && studentRes == "Y") {
studentTuition = studentCredit * 432.00;
studentFees = (studentCredit * 28.37) + 900.00;
}
else {
studentTuition = studentCredit * 841.00;
studentFees = (studentCredit * 28.37) + 900.00;
}
}
}
else {
if(studentLife == "f" || studentLife == "F") {
if(studentRes == "y" && studentRes == "Y") {
studentTuition = 5185.00;
studentFees = 342.14;
}
else {
studentTuition = 10095.00;
studentFees = 342.14;
}
}
else {
if(studentRes == "y" && studentRes == "Y") {
studentTuition = studentCredit * 432.00;
studentFees = studentCredit * 28.37;
}
else {
studentTuition = studentCredit * 841.00;
studentFees = studentCredit * 28.37;
}
}
}
}
我知道这是一个很多问... 感谢您对任何人谁可以帮助我了解如何做到这一点更好一点！
将参数从原型添加到gradBill（）和undergradBill（）的实现中。 – dgsomerton
因为这些函数声明在C++中是无效的，所以你需要[从一个好的初学者书开始]（http://stackoverflow.com/questions/388242/the-definitive-c-book-guide-and-list）给你错误。 –
具有默认参数的参数必须在参数列表的末尾形成一个连续的组。所以如果你想给finalBill一个默认参数，这应该作为最后一个参数传递，或者你也应该为下面的参数提供一个默认值。 – Stefano