c++ - 使用星期几的类
问题描述
我有一个任务，基本上要求我使用一个类来根据用户 EX 的输入输出星期几：用户输入sat（前三个字母）-> output = This day of the week is: 6。我们还需要程序在用户指定的日期之后输出接下来的六天，例如：
输入：周二
输出：一周中的这一天是：2 一周中的这一天是：3 一周中的这一天是：4 一周中的这一天是：5 一周中的这一天是：6 一周中的这一天是：7一周中的这一天是：1
我的程序有点混乱，因为我最初误解了这个问题。我能够开发一个功能正常的程序，允许用户输入当天的数字，但不能输入前三个字母，因为这部分代码似乎没有任何功能。
任何建议或解决方案将不胜感激。先感谢您。
#include <iostream>
#include <string>
using namespace std;
//
// Definition of the DayOfWeek class
//
class DayOfWeek
{
public:
DayOfWeek(int dayNum);
// Precondition: The parameter dayNum contains a valid
// day number (1 - 7)
// Postcondition: The member variable day has been set to
// the value of the parameter dayNum.
DayOfWeek();
// Sets the member variable month to 1 (defaults to January).
DayOfWeek(char fL, char sL, char tL);
void outputDayNumber();
// Postcondition: The member variable day has been output
// to the screen if it is valid; otherwise a "not valid"
// message is printed.
void outputDayLetters();
// Postcondition: The first three letters of the name of the
// day has been output to the screen if the day is
// valid (1 - 12); otherwise a message indicating the month
// is not valid is output.
DayOfWeek NextDay();
// Precondition: The month is defined and valid.
// Returns the next day as an object of type Day.
private:
int day;
};
int main()
{
//
// Variable declarations
//
int DayNum;
string DayWord;
char letter1, letter2, letter3; // first 3 letters of the day
char testAgain; // y or n - loop control
//
// Loop to test the next month function
//
do {
cout << endl;
cout << "Enter a day number: ";
cin >> DayNum;
DayOfWeek testDay(DayNum);
cout << endl;
cout << "This day ..." << endl;
testDay.outputDayNumber();
testDay.outputDayLetters();
DayOfWeek next = testDay.NextDay();
cout << endl;
cout << "Next day ..." << endl;
next.outputDayNumber();
next.outputDayLetters();
//
// See if user wants to try another month
//
cout << endl;
cout << "Do you want to test again? (y or n) ";
cin >> testAgain;
} while (testAgain == 'y' || testAgain == 'Y');
return 0;
}
DayOfWeek::DayOfWeek()
{
day = 1;
}
DayOfWeek::DayOfWeek(int dayNum)
{
if (dayNum >= 1 && dayNum <= 7)
day = dayNum;
else {
dayNum = 1;
}
}
void DayOfWeek::outputDayNumber()
{
if (day >= 1 && day <= 7)
cout << "Day: " << day << endl;
else
cout << "Error - The day is not valid!" << endl;
}
void DayOfWeek::outputDayLetters()
{
switch (day)
{
case 1:
cout << "1" << endl;
break;
case 2:
cout << "2" << endl;
break;
case 3:
cout << "3" << endl;
break;
case 4:
cout << "4" << endl;
break;
case 5:
cout << "5" << endl;
break;
case 6:
cout << "6" << endl;
break;
case 7:
cout << "7" << endl;
break;
default:
cout << "Error - the day is not valid!" << endl;
}
}
DayOfWeek::DayOfWeek(char firstL, char secondL, char thirdL)
{
/**
*check to for the first characters or letter of the day
*prints the day based on the characters user input
*check if the characters is valid
*/
if (firstL >= 65 && firstL <= 90) {
firstL += 32;
}
if (secondL >= 65 && secondL <= 90) {
secondL += 32;
}
if (thirdL >= 65 && thirdL <= 90) {
thirdL += 32;
}
if (firstL == 'm' && secondL == 'o' && thirdL == 'n') {
day = 1;
}
else if (firstL == 't' && secondL == 'u' && thirdL == 'e') {
day = 2;
}
else if (firstL == 'w' && secondL == 'e' && thirdL == 'd') {
day = 3;
}
else if (firstL == 't' && secondL == 'h' && thirdL == 'u') {
day = 4;
}
else if (firstL == 'f' && secondL == 'r' && thirdL == 'i') {
day = 5;
}
else if (firstL == 's' && secondL == 'a' && thirdL == 't') {
day = 6;
}
else if (firstL == 's' && secondL == 'u' && thirdL == 'n') {
day = 7;
}
else {
day = 0;
cout << "Invalid Day" << endl;
}
}
DayOfWeek DayOfWeek::NextDay() {
int d = (day % 7) + 1;
return DayOfWeek(d);
}
更新：完全改变了我的代码，但仍然需要实现第二天和接下来的 6 天功能。新代码：
#include <iostream>
#include <string>
using namespace std;
class DayOfWeek
{
string day;
public:
DayOfWeek();
DayOfWeek(string day_name);
void print_car(ostream& ins);
};
int main() {
string day_name;
cout << "Enter the first three letters of the day :" << endl;
cin >> day_name;
DayOfWeek my_car(day_name);
my_car.print_car(cout);
return 0;
}
DayOfWeek::DayOfWeek(string day_name) {
day = day_name;
}
void DayOfWeek::print_car(ostream& outs) {
if (day == "Mon" || day == "mon") {
outs << "This is day 1 of the week" << endl;
}
if (day == "Tue" || day == "tue") {
outs << "This is day 2 of the week" << endl;
}
if (day == "Wed" || day == "wed") {
outs << "This is day 3 of the week" << endl;
}
if (day == "Thu" || day == "thu") {
outs << "This is day 4 of the week" << endl;
}
if (day == "Fri" || day == "fri") {
outs << "This is day 5 of the week" << endl;
}
if (day == "Sat" || day == "sat") {
outs << "This is day 6 of the week" << endl;
}
if (day == "Sun" || day == "sun") {
outs << "This is day 7 of the week" << endl;
}
}
最终更新：
我几乎是最终解决方案，但我在为我的问题的最后部分声明一个新对象时遇到问题。
代码在这里...
#include <iostream>
#include <string>
using namespace std;
class DayOfWeek
{
string day;
// int nday;
public:
DayOfWeek();
DayOfWeek(string day_name);
void print_day(ostream& ins);
};
int main() {
string day_name;
int nday;
cout << "Enter the first three letters of the day :" << endl;
cin >> day_name;
DayOfWeek week_day(day_name);
week_day.print_day(cout);
DayOfWeek next_day;
int d = _____;
int current = (d % 7) + 1;
int count = 0;
while (count < 7) {
next_day = DayOfWeek(current);
next_day.print_day(cout);
count++;
}
return 0;
}
DayOfWeek::DayOfWeek(string day_name) {
day = day_name;
}
void DayOfWeek::print_day(ostream& outs) {
int dayNumber = 0;
if (day == "Mon" || day == "mon") {
dayNumber = 1;
}
if (day == "Tue" || day == "tue") {
dayNumber = 2;
}
if (day == "Wed" || day == "wed") {
dayNumber = 3;
}
if (day == "Thu" || day == "thu") {
dayNumber = 4;
}
if (day == "Fri" || day == "fri") {
dayNumber = 5;
}
if (day == "Sat" || day == "sat") {
dayNumber = 6;
}
if (day == "Sun" || day == "sun") {
dayNumber = 7;
}
outs << "This is day " << dayNumber << " of the week." << endl;
}
我有一些问题能够将用户输入的日期名称转换为可以用来插入 next_day 函数的整数。我在while循环中也有错误
while (count < 7) {
next_day = DayOfWeek(current);
next_day.print_day(cout);
count++;
}
具体线路：
next_day = DayOfWeek(current);
该错误表明没有与参数列表匹配的 DayOfWeek::DayOfWeek 实例。如果不是因为这几个颠簸，我觉得我快到了。
解决方案
下面的代码应该做一些你需要的。
我没有使用字符，而是使用了字符串。这样，您可以一次比较整个字符串，而不是一次比较 1 个字符。
此外，为了将输入与日词进行比较，我创建了一个字符串数组。该索引对应于日期，即 0=星期日，1=星期一等。
这有两个原因，我们可以轻松地与循环进行比较，一旦我们找到匹配的日期，我们就抓住索引，我们就有了我们的天数。存储该数字，然后我们可以将其作为日期编号返回，或者将日期用作数组中的索引来返回日期单词。
希望这很清楚，您仍然需要创建一个函数以在第二天返回，但是 3 个字母输入应该可以工作。
#include <iostream>
#include <cctype> // std::tolower
#include <algorithm> // std::transform
class DayOfWeek
{
private:
const static std::string days[7];
private:
int day;
public:
DayOfWeek();
DayOfWeek(int);
DayOfWeek(std::string);
void outputDayNumber();
void outputDayLetters();
};
// if we have an array of strings, we can use these for comparison and also Day value
const std::string DayOfWeek::days[7] = {"sun", "mon", "tue", "wed", "thu", "fri", "sat"};
DayOfWeek::DayOfWeek() {
}
DayOfWeek::DayOfWeek(int dayNum)
{
day = dayNum;
}
DayOfWeek::DayOfWeek(std::string dayWord)
{
day = 0; // set Sunday as default
// truncate the string to 3 letters
if (dayWord.length() > 3)
dayWord = dayWord.substr(0, 3);
// to lower case - makes comparison case insensitive
std::transform(dayWord.begin(), dayWord.end(), dayWord.begin(), [](unsigned char c) { return std::tolower(c);});
// compare with our list of strings, if none found, it will stay as default
for (int i = 0; i < 7; ++i)
if (days[i] == dayWord)
{
day = i;
break;
}
}
void DayOfWeek::outputDayLetters() {
std::cout << std::endl << "Day Letters: " << days[day];
}
void DayOfWeek::outputDayNumber() {
std::cout << std::endl << "Day Numbers: " << day;
}
int main()
{
int dayNum;
std::string dayWord;
std::cout << std::endl << "Enter a weekday: ";
std::cin >> dayWord;
std::cout << std::endl << "You entered " << dayWord;
DayOfWeek dayObject = DayOfWeek(dayWord);
dayObject.outputDayNumber();
dayObject.outputDayLetters();
}