不知道如何总是从较大的数中减去较小的数字

Question

我有整个程序，除了它总是从较大的数中减去较小的数的部分。我一直在试图找到它，但我找不到任何东西来帮助我。这是我需要帮助的唯一部分。

这是代码。

#include <iostream> 
#include <iomanip> 
#include <cmath> 
using namespace std; 

//function prototype 
int getRandomNumber(int lower, int upper); 

int main() 
{ 
//declare variables 
int smallest = 0; 
int largest = 0; 
int num1 = 0; 
int num2 = 0; 
int correctAnswer = 0; 
int userAnswer = 0; 

//initialize rand function 
srand(static_cast<int>(time(0))); 

cout << "Smallest Integer: "; 
cin >> smallest; 
cout << "Largest Integer: "; 
cin >> largest; 
cout << endl; 

for (int x = 1; x < 6; x += 1) 
{ 
//generate two random integers 
//from smallest through largest, then 
//calculate the sum 
num1 = getRandomNumber(smallest, largest); 
num2 = getRandomNumber(smallest, largest); 
correctAnswer = num1 - num2; 

//display addition problem and get user's answer 
cout << "what is the difference of " << num1 <<" - " << num2 << " ? "; 
cin >> userAnswer; 

//determine wether user's answer is correct 
if (userAnswer == correctAnswer) 
cout << "Correct"; 
else 
cout << " Sorry, the correct answer is " << correctAnswer << "."; 
//end if 
cout << endl << endl; 
} //end for 

return 0; 
} //end of main function 

//*****function definitions***** 
int getRandomNumber(int lower, int upper) 
{ 
int randInteger = 0; 
//generate random integer from lower through upper 
randInteger = lower + rand() % (upper - lower + 1); 
return randInteger; 
} //end of getRandomNumber function 

need help! 

Answer 1

如果你只是在两个数之间的差异后，为什么不使用abs（num1 - num2）？ 然后你就不必关心订单了。

http://www.cplusplus.com/reference/clibrary/cmath/abs/

Answer 2

似乎很简单。

if (num1 < num2) 
    correctAnswer = num2 - num1; 
else 
    correctAnswer = num1 - num2; 

Answer 3

只是把逻辑放到一个函数中，并做一个简单的布尔检查来决定返回哪个结果。

int SubstractSmallerNumber(int num1, int num2){ 
    if(num1 < num2) return num2 - num1; 
    else return num1 - num2; 
} 

这是一个蛮力方法，您可以找到更智能的方法来解决问题。 想想绝对值。如果您采用减法的绝对值，您将获得相同的净效应。