C++ 年龄计算器 - 查找两个日期之间时间的最有效方程式

Question

我正在尝试用 C++ 创建一个年龄计算器，它接受用户输入的当前月份、日期和年份，以及用户的生日 (MM DD YYYY)。其余功能正常工作，但我的 calculateAge() 功能有问题。

任何人都可以在我的 calculateAge() 函数中看到我的方程式的问题，或者我可以如何提高它的效率吗？

编辑:完整代码

    #include <iostream>

using namespace std;

main () {

    //declare local variables
    bool valid, validBirthday;
    int cmonth, cday, cyear;
    int bmonth, bday, byear;
    int ageYears, ageMonths, ageDays;
    char answer;
    const int MAXGUESSES = 3;

    //function declarations
    bool enterDate (int&, int&, int&, const int);
    bool enterBirthDate (int, int, int, int&, int&, int&, const int);
    void calculateAge (int, int, int, int, int, int, int&, int&, int&);

    //prompt the user for todays date and invoke the enterDate() function
    cout << "Please enter today's date, ";
    valid = enterDate(cmonth, cday, cyear, MAXGUESSES);

    //if validDate() function doesn't recognize a valid date after three tries
    //the user is alerted
    if (valid == false)
        cout << endl;
    else

    //if the date was valid show the user the date they entered and ask
    //if they would like to calculate their age.
    if (valid == true) {
        cout << "Date entered is: " << cmonth << '/' << cday << '/' << cyear << endl;

        cout << "Would you like to see how old you are? (y/n) ";
        cin >> answer;

        if (answer == 'N' || answer == 'n')
            cout << "OK" << endl;
        else

        //if the user would like to see their age, call the enterBirthDate
        //function and assign the return value to the boolean variable
        //validBirthDate
        if (answer == 'Y' || answer == 'y') {
            if (validBirthday = enterBirthDate (cmonth, cday, cyear, bmonth, bday, byear, MAXGUESSES) == true) {

            cout << "Date entered is: " << bmonth << '/' << bday << '/' << byear << endl;       

            //call the calculateAge() function to calculate the user's age
            calculateAge(bmonth, bday, byear, cmonth, cday, cyear, ageYears, ageMonths, ageDays);

            //display results
            cout << "You are " << ageYears << " years, " << ageMonths << " months, and " << ageDays << " days old." << endl;

            //display a special result if it is the users birthday
            if (bmonth == cmonth && bday == cday)
                cout << "Happy Birthday!" << endl;
            }

            else
                cout << "You have entered an invalid birth day." << endl;

        } //end if answer is yes

        else //if answe is not yes or no
            cout << "You did not enter 'y' or 'n'" << endl;


    } //end if current date is valid
}

函数

#include <iostream>

using namespace std;

//function definition for enterDate() - the function that prompts
//the user for input and parses input into months, days, and years
//and then calls the validDate() function to make sure the entered 
//date is valid.

bool enterDate (int&month, int&day, int&year, const int MAXGUESSES) {

    bool valid;
    int counter = 1;

    bool validDate(int&, int&, int&);

    cout << "Please enter the date as MM DD YYYY: ";
    cin >> month >> day >> year;

    valid = validDate(month, day, year);

    // use the constant MAXGUESSES and the variable counter to
    // allow the user only three tries to enter a valid date

    if (valid == false) {
        while (valid == false && counter < MAXGUESSES) {
            counter++;
            cout << "The entered date is invalid, please re-enter: ";
            cin >> month >> day >> year;
            valid = validDate(month, day, year);

        }

    // if the user reaches the limit of three guesses, alert them
    // and bring an end to the program

    cout << "You have reached the limit for invalid dates." << endl;
    }

    return(valid);

}

// function definition for enterBirthDate() which prompts the user to enter
// their birthdate and invokes the enterDate() function to parse the input and
// the dateBefore() function to make sure the entered birth date occurs before
// the current date entered by the user

bool enterBirthDate (int cmonth, int cday, int cyear, int&bmonth, int&bday, int&byear, const int MAXGUESSES) {

    bool valid;
    bool valid2;

    bool dateBefore (int, int, int, int, int, int);
    bool enterDate (int&, int&, int&, const int);

    cout << "We need to know your date of birth, ";

    // call function enterDate() to prompt the user for input and parse
    // the input into b(irthday)month, bday, and byear

    valid = enterDate(bmonth, bday, byear, MAXGUESSES);

    //if the birth date entered by the user is a valid date, make sure
    //that the birth date occurs before the current date supplied by
    //the user in enterDate()

    if (valid == true)
        valid2 = dateBefore(cmonth, cday, cyear, bmonth, bday, byear);

    return(valid2);

}

//function definition for dateBefore() (invoked by enterBirthDate()  which
//compares variables c(urrent)month cday, and cyear to b(irth)month, bday, 
//and byear to make sure the birthday occurs before the current date supplied by the user

bool dateBefore (int cmonth, int cday, int cyear, int bmonth, int bday, int byear) {

    bool valid;


    //if the birth year is greater than the current year assign the boolean
    //variable 0 (false) to valid, indicating an invalid birth date

    if (byear > cyear)
        valid = false;
    else

    //if birth year is equal to the current year, perform relational operations
    //on the bmonth and cmonth variables to determine which date occured first

    if (byear == cyear) {

        //if the birth year and current year are the same, but the birth
        //month is less than the current month, assign the value of true
        //to the boolean variable valid

        if (bmonth < cmonth) 
            valid = true;
        else

        //if the bmonth = cmonth perform relational operations on bday and cday
        if (bmonth == cmonth)

            //if the bday is less than the cday assign true to the boolean variable valid
            if (bday < cday)
                valid = true;
            else
                //if the bday is greater than the cday assign the value false to valid
                valid = false;
        else

        //if bmonth is greater than the cmonth and byear is equal to the cyear 
        //assign false to valid, indicating an invalid birth day

        if (bmonth > cmonth)
            valid = false;
    else
    //if the cyear is greater than the byear assign the value of false to valid
    if (byear < cyear)
        valid = false;
    }

    return(valid);
}


//function definition for validDate() (invoked by enterDate() ) which uses variables of day, month, and year
//to make sure that the date entered is valid based on month, day, and year variables
bool validDate (int&month, int&day, int&year) {

    //local variables
    bool valid;
    int maxDay;

    //function declaration
    int getLastDay (int);

    //calculate maximum day based on month
    maxDay = getLastDay(month);

    //if the month is less than zero or greater than 12 assign the value false to
    //the boolean variable valid indicating an invalid date
    if (month < 0 || month > 12)
        valid = false;

    else

    //if the month is valid make sure that the day falls inbetween 1 and the maximum day
    //associated with the month entered

    if (month > 0 && month <= 12) {
        if (day > 0 && day <= maxDay)
            valid = true;
        else
            valid = false;
    }

    return (valid); 
}

//function definition for calculareAge(). Invoked by main(), calculate age accept parameters bmonth, bday, byear,
//cmonth, cday, and cyear (by value) to perform calculations and relational operations to determine age. The parameters
//ageYears, ageMonths, and ageDays are passed by reference so they can be output in the main() program.

void calculateAge (int bmonth, int bday, int byear, int cmonth, int cday, int cyear, int&ageYears, int&ageMonths, int&ageDays) {

    //local variable
    int maxDay;

    //function declaration
    int getLastDay (int);

    maxDay = getLastDay (bmonth);

    if (cyear >= byear && cmonth >= bmonth && cday >= bday){
        ageYears = cyear - byear;
        ageMonths = cmonth - bmonth;
        ageDays = cday - bday;

    }
    else

    if (cyear > byear) {
        if (cmonth >= bmonth) {
            if (cday < bday) {
                ageYears = cyear - byear;
                ageMonths = cmonth - bmonth - 1;
                ageDays = maxDay - bday + cday;
            }
        }
        else
        if (cmonth < bmonth) {
            if (cday > bday) {
                ageYears = cyear - byear - 1;
                ageMonths = 12 - bmonth + cmonth;
                ageDays = cday - bday;
            }
            else
            if (bday > cday) {
                ageYears = cyear - byear - 1;
                ageMonths = 12 - bmonth + cmonth - 1;
                ageDays = maxDay - bday + cday;
            }
        }
    }

}

//function definition for getLastDay(), uses the month entered to calculate the maximum
//valid day for that month

int getLastDay (int month) {

    int maxDay;

    switch (month) {
        case 4:
        case 6:
        case 9:
        case 11:
            maxDay = 30;
            break;
        case 1:
        case 3:
        case 5:
        case 7:
        case 8:
        case 10:
        case 12:
            maxDay = 31;
            break;
        case 2:
            maxDay = 28;
    }

    return(maxDay);
}

Answer 1

好吧，看起来您的代码在以下情况下会失败:1 9 2001 y 1 10 2000。

给日历中的每一天一个常量值怎么样？

我修改了您的 calculateAge() 函数并创建了另一个名为 getInt() 的函数，它给出了相应的日期常量值。

因此，减去两个日期很容易得到结果。看下面的代码就清楚了。

请随时询问有关它的任何问题。

新的 getInt 函数:

int getInt(int y, int m, int d)
{
    int ret = y*365;

    //function declaration
    int getLastDay (int);

    for (int i = 1; i<m; i++)
        ret+=getLastDay(i);
    ret+=d;
    return ret;
}

修改后的calculateAge函数:

//function definition for calculareAge(). Invoked by main(), calculate age accept parameters bmonth, bday, byear,
//cmonth, cday, and cyear (by value) to perform calculations and relational operations to determine age. The parameters
//ageYears, ageMonths, and ageDays are passed by reference so they can be output in the main() program.

void calculateAge (int bmonth, int bday, int byear, int cmonth, int cday, int cyear, int&ageYears, int&ageMonths, int&ageDays) {

    //local variable
    int maxDay;

    //function declaration
    int getLastDay (int);

    int now = getInt(cyear,cmonth,cday);
    int birthday = getInt(byear,bmonth,bday);
    if(now<birthday) return;
    int diff = now-birthday;
    ageYears = (diff)/365;

    diff-=(365*ageYears);

    ageMonths = 0;
    int rest;
    while(1)
    {
        rest = getLastDay(ageMonths+1);
        if(diff>=rest)
        {
            diff-=rest;
            ageMonths++;
        }
        else break;
    }
    ageDays = diff;
}