请放轻松,因为我是 C++ 的新手,目前正在上编程入门课:)
我目前在正确编译 do\while 语句时遇到问题。我的目标是输入以下内容,直到输入标记值 -1,这将结束该过程并提供我的值的累计总数。
以下是我需要为每个实体输入的值:
gallons used
starting mileage
ending mileage
miles driven
miles per gallon
一旦输入标记值,它就应该为所有合并的实体计算以下值:
total gallons used
total miles driven
overall average miles per gallon
以下是我到目前为止的内容,但输入 -1 时并未结束。当输入 -1 时,我还没有添加尚未使用的最终值,因为我不确定如何继续并试图让第 1 部分首先正常工作。下面是我的代码(请原谅评论):
int main(void)
{
StartUp(); //indicates beginning of code
double startmileage{ 0 }; //indicates starting mileage, initialized at the value of 0
double endmileage{ 0 }; //indicates ending mileage, initialized at the value of 0
double milesdriven{ 0 }; //indicates total miles driven, initialized at the value of 0
double gallonsused{ 0 }; //indicates total gallons used, initialized at the value of 0
long double milespergallon{ 0 }; //indicates total miles per gallon, initialized at the value of 0
do
{
cout << "enter the gallons used: "; //prompts user to enter total number of gallons used for trip
cin >> gallonsused; //user enters data
cout << "enter starting mileage: "; //prompts user to enter start mileage for trip
cin >> startmileage; //user enters data
cout << "enter ending mileage: "; //prompts user to enter end mileage for trip
cin >> endmileage; //user enters data
milesdriven = startmileage + endmileage; //calculates total miles driven
cout << "Miles Driven: " << milesdriven << endl; //outputs total miles driven to screen
milespergallon = milesdriven / gallonsused; //calculates total miles per gallon
cout << "Miles Per Gallon: " << milespergallon << endl; //outputs miles per gallon to screen
}
while (gallonsused != -1);
WrapUp(); //indicates end of code
return Success;
}
这是正在发生的事情:
enter the gallons used: 12.8
enter starting mileage: 0
enter ending mileage: 277
Miles Driven: 277
Miles Per Gallon: 21.6406
enter the gallons used: -1
enter starting mileage:
如您所见,它会循环,但不会在输入标记值时停止
如有任何帮助,我们将不胜感激!
谢谢!
最佳答案
在循环结束之前,您不会测试 gallonsused != -1
,在用户响应所有其他提示并计算里程之后。
不要使用 do-while()
,而是在用户输入后立即测试 gallonsused
,然后跳出循环。
您还需要总行驶英里数和使用的总加仑数的变量。每次输入后,您将该行程的值添加到总计中,并在最后将它们用于总计。
double totalmiles = 0;
double totalgallons = 0;
while (true)
{
cout << "enter the gallons used: "; //prompts user to enter total number of gallons used for trip
cin >> gallonsused; //user enters data
if (gallonsused == -1) { // Check for sentinel
break;
}
totalgallons += gallonsused;
cout << "enter starting mileage: "; //prompts user to enter start mileage for trip
cin >> startmileage; //user enters data
cout << "enter ending mileage: "; //prompts user to enter end mileage for trip
cin >> endmileage; //user enters data
milesdriven = startmileage + endmileage; //calculates total miles driven
totalmiles += milesdriven;
cout << "Miles Driven: " << milesdriven << endl; //outputs total miles driven to screen
milespergallon = milesdriven / gallonsused; //calculates total miles per gallon
cout << "Miles Per Gallon: " << milespergallon << endl; //outputs miles per gallon to screen
}
// Show grand totals
cout << "Grand totals:" << endl;
cout << "Total Miles Driven: " << totalmiles << endl;
cout << "Total Miles Per Gallon: " << totalmiles/totalgallons << endl;
WrapUp();
关于c++ - do\while 语句将无法正确编译(初学者),我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/39563754/