Question

我是C ++的新手，这是家庭作业。我不明白发生了什么。当我运行这个时，一切正常，如果我输入60000当前工资和.05加薪，但如果我输入52000当前工资和.23加薪，那么追溯工资为5982.00而不是5980.00它与小数或其他东西有关吗？我真的不知道。提前谢谢。

// Variables
char fullName[30];  // The user's full name - INPUT
int currentAnnual;  // The users's current annual salary - INPUT
float percentIncrease; // The percent increase due on the
                       //   current annual salary - INPUT
// The retroactive pay
float retroactive;
// The new monthly salary based on the pay increase and the new salary
float monthlySalary;
// The new salary the user should receive based on their old salary
    //      and their pay increase
float newSalary;

for(int lcv = 1; lcv <= 3; lcv++)
{
    // INPUT
    cout << "What is your full name? ";
    cin.getline(fullName, 30);
    cout << "What is your current salary? ";
    cin >> currentAnnual;
    cout << "What is your pay increase (please input percentage in"
            "decimal format)? ";
    cin >> percentIncrease;

    // PROCESSING
    newSalary = (currentAnnual * percentIncrease) + currentAnnual;
    monthlySalary = newSalary / 12;
    retroactive = (monthlySalary - (currentAnnual / 12)) * 6;

    // OUTPUT
    cout << endl;
    cout << fullName << "'s Salary Information\n";
    cout << left << setw(15) << "New Salary" << setw(19) << "Monthly Salary"
            << "Retroactive Pay\n";
    cout << setprecision(2);
    cout << fixed;
    cout << right << setw(10) << newSalary << setw(19) << monthlySalary
                << setw(20) << retroactive << endl << endl;
    cout << "<Press enter to continue>";
    cin.ignore(100, '\n');
    cin.ignore(1000, '\n');
    cout << endl;
}

Answer 1

将currentAnnual / 12更改为currentAnnual / 12.0以强制执行浮点计算。否则，计算的那部分将四舍五入到下面最接近的整数。

Answer 2

currentAnnual / 12

C中两个整数的除法是“整数除法”（它给出一个整数），我想你不想这样。一种解决方案是将其更改为currentAnnual / 12.0。无论如何，了解这里发生的事情非常重要。

Answer 3

您应该monthlySalary = newSalary / 12.0;而不是monthlySalary = newSalary / 12;，因此您必须指定要除以浮点数。否则结果将是整数。例如125./12 = 10，但125./12. = 10.41(6)。当然，你会得到错误的结果。

尝试向所有常量添加.0或.。

Answer 4

浮点计算不如您预期的那么准确。尝试在上面的代码中用float替换double（double是一个“双精度浮点数”;它可以存储比float更多的值，并且更精确）。

此外，操作顺序有时很重要，因此您可能希望将retroactive计算重新排序为

6 * monthlySalery - currentAnnual / 0.5;

并尝试其他组合以查看最佳效果。

计算问题C ++

4 个答案: