为什么我的第一个if语句起作用，但是我的其他if语句不起作用

Question

Why does my first if statement work, but my else if statement doesn't? Just hoping someone can see something I may be missing. When I enter in a time between 800 and 1800 the code continues fine, but when I enter in 600 it jumps to my else statement that I entered in an illegal format.

if ((time_start >= 800) && (time_start <= 1800))
    {
    cout << "How many minutes did your call last? ";
    cin >> minutes;
    cost = minutes * 0.40;
    cout << setprecision(2) << fixed << cost;
    system("pause");
    keepgoing = false;
} 
else if ((time_start < 800) && (time_start > 1800))
{
    cout << "How many minutes did your call last? ";
    cin >> minutes;
    cost = minutes * 0.25;
    cout << setprecision(2) << fixed << cost;
    system("pause");
    keepgoing = false;
}

Answer 1

else if ((time_start < 800) && (time_start > 1800))

一个数字不可能小于800且大于1800。我假设您的意思是：

else if ((time_start < 800) || (time_start > 1800))

Answer 2

You've got a 'logic bug' : use || instead of && in else if . It's simply impossible for a number to be less than 800 and greater than 1800 at the same time .

Answer 3

As soon as I asked this question I realized my second else if statement should be an or || statement instead of &&.

Answer 4

change

else if ((time_start < 800) (time_start > 1800

to

else if ((time_start < 800) || (time_start > 1800

Answer 5

You can simplify the code to this, else statement is not needed. Store the value in coeficient variable, that's needed to be defined before

// else coef (default value)
float coef = 0.25;
if ((time_start >= 800) && (time_start <= 1800))
{
    coef = 0.40; // if true
}
cout << "How many minutes did your call last? ";
cin >> minutes;
// use coef here and remove duplicate calls
cost = minutes * coef;
cout << setprecision(2) << fixed << cost;
system("pause");
keepgoing = false;