我在第一次C ++课程中遇到了很多麻烦。
我已经想出如何让它正确地询问用户他们想要使用什么操作（加，减，乘），生成0-9之间的随机数，以及如何要求用户解决问题和如果它是正确的或不正确的。
在此之后，程序应该询问用户是否要继续（通过按y）或退出（按Q），当用户输入任何其他字母时会显示错误消息，但是某些原因导致程序在运行程序时不显示。
如何让循环正常工作，允许我做最后的提示，然后只有在按Y时重复整个程序或在按Q时退出？
注意：我对编码很新，这是我的第一个C ++课程，所以我还不知道如何使这段代码更简洁：
#include <iostream>
#include <cstdio>
#include <time.h>
#include <stdlib.h>
using namespace std;
int main()
{
while (true)
{
// Generate two random single-digit integers btwn 0-9
srand(time(0));
int num1 = rand() % 10;
int num2 = rand() % 10;
int operation, play, num3, guess, Y, Q;
// If num1 < num2, swap num1 with num2
if (num1 < num2)
{
int temp = num1;
num1 = num2;
num2 = temp;
}
cout << "Choose an operation." << endl;
cout << "Enter 1 to add, 2 to subtract, or 3 to multiply: " << endl;
cin >> operation;
if (operation > 3 || operation < 1)
{
cout << "Your operation choice isn't valid! Please try again, using 1, 2, or 3." << endl;
cout << "Choose an operation." << endl;
cout << "Enter 1 to add, 2 to subtract, or 3 to multiply: " << endl;
cin >> operation;
}
else if (operation == 1)
{
cout << "You chose addition." << endl;
num3 = num1 + num2;
cout << "What is " << num1 << " + " << num2 << " ?: " << endl;
cin >> guess;
if (guess != num3)
{
cout << "That is incorrect. Please try again." << endl;
cout << "" << endl;
cout << "What is " << num1 << " + " << num2 << " ?: " << endl;
cin >> guess;
}
else if (guess == num3)
{
cout << "That is correct!" << endl;
cout << "" << endl;
}
}
else if (operation == 2)
{
cout << "You chose subtraction." << endl;
num3 = num1 + num2;
cout << "What is " << num1 << " - " << num2 << " ?: " << endl;
cin >> guess;
if (guess != num3)
{
cout << "That is incorrect. Please try again." << endl;
cout << "" << endl;
cout << "What is " << num1 << " - " << num2 << " ?: " << endl;
cin >> guess;
}
else if (guess == num3)
{
cout << "That is correct!" << endl;
cout << "" << endl;
}
}
else if (operation == 3)
{
cout << "You chose multiplication." << endl;
num3 = num1 * num2;
cout << "What is " << num1 << " * " << num2 << " ?: " << endl;
cin >> guess;
if (guess != num3)
{
cout << "That is incorrect. Please try again." << endl;
cout << "" << endl;
cout << "What is " << num1 << " * " << num2 << " ?: " << endl;
cin >> guess;
}
else if (guess == num3)
{
cout << "That is correct!" << endl;
cout << "" << endl;
}
}
while (guess != num3)
{
int play, Y, Q;
cout << "Would you like to play again? Press Y for yes or Q for
quit" << endl;
cin >> play;
if (play != Y || play != Q)
{
cout << "That is not a valid choice. Please choose Y for yes
or Q to quit. " << endl;
cin >> play;
}
else
{
if (play == Y)
{
cout << "Thank you for playing! Let's play again!" << endl;
cout << "" << endl;
}
else if (play == Q)
{
cout << "Thank you for playing! See you next time!" << endl;
cout << "" << endl;
}
break;
}
}
}
return 0;
}
答案 0 :(得分：2)
这里的事情很少......
将srand(time(0));移出while循环并移至main的顶部。如果您在同一秒内重复播种（如果time(0)没有改变），您将获得两次相同的“随机”数字。
num3如果他们没有输入有效的operation？您永远不会num3初始化，因此如果他们没有选择有效的operation，num3会有垃圾值。然后你继续运行一个循环，其条件取决于num3的值！ （while (guess != num3)）
else { ... if {与else if { 在最后一个循环中，将if (play == Y)和else if (play == Q)从嵌套if中取出，并将其设为else if。
while (guess != num3)真的对吗？你想循环，直到他们输入有效的输入，那么为什么你在guess != num3时循环？
答案 1 :(得分：1)
使用开关盒可以更好地选择正确的操作：
Switch(operation) {case 1: break;}
您还需要添加一个 所以正确的代码应该是这样的：
#include <iostream>
#include <cstdio>
#include <time.h>
#include <stdlib.h>
using namespace std;
int main()
{
int operation, num3, guess,num1,num2,temp;
srand(time(0));
char play;
do
{
// Generate two random single-digit integers btwn 0-9
num1 = rand() % 10;
num2 = rand() % 10;
// If num1 < num2, swap num1 with num2
if (num1 < num2)
{
temp = num1;
num1 = num2;
num2 = temp;
}
do
{
cout << "Choose an operation." << endl;
cout << "Enter 1 to add, 2 to subtract, or 3 to multiply: " << endl;
cin >> operation;
if (operation > 3 || operation < 1)
{
cout << "Your operation choice isn't valid! Please try again, using 1, 2, or 3." << endl;
}
}while(operation>3 || operation<1);
switch(operation)
{
case 1:
cout << "You chose addition." << endl;
num3 = num1 + num2;
cout << "What is " << num1 << " + " << num2 << " ?: " << endl;
cin >> guess;
if (guess != num3)
{
cout << "That is incorrect. Please try again." << endl;
cout << "" << endl;
cout << "What is " << num1 << " + " << num2 << " ?: " << endl;
cin >> guess;
}
else if (guess == num3)
{
cout << "That is correct!" << endl;
cout << "" << endl;
}
break;
case 2:
cout << "You chose subtraction." << endl;
num3 = num1 - num2;
cout << "What is " << num1 << " - " << num2 << " ?: " << endl;
cin >> guess;
if (guess != num3)
{
cout << "That is incorrect. Please try again." << endl;
cout << "" << endl;
cout << "What is " << num1 << " - " << num2 << " ?: " << endl;
cin >> guess;
}
else if (guess == num3)
{
cout << "That is correct!" << endl;
cout << "" << endl;
}
break;
case 3:
cout << "You chose multiplication." << endl;
num3 = num1 * num2;
cout << "What is " << num1 << " * " << num2 << " ?: " << endl;
cin >> guess;
if (guess != num3)
{
cout << "That is incorrect. Please try again." << endl;
cout << "" << endl;
cout << "What is " << num1 << " * " << num2 << " ?: " << endl;
cin >> guess;
}
else if (guess == num3)
{
cout << "That is correct!" << endl;
cout << "" << endl;
}
break;
}
do
{
cout << "Would you like to play again? Press Y for yes or Q for quit" << endl;
cin >> play;
if (play != 'Y' && play != 'Q')
{
cout << "That is not a valid choice. Please choose Y for yes or Q to quit. " << endl;
}
}while(play!='Y' && play!='Q');
if (play == 'Y')
{
cout << "Thank you for playing! Let's play again!" << endl;
cout << "" << endl;
}
else
{
cout << "Thank you for playing! See you next time!" << endl;
cout << "" << endl;
}
}while(play=='Y');
return 0;
}
答案 2 :(得分：1)
所以正确的代码是：
PS F:\Nick\Angular\firebase-work> npm update @angular/core
Package "@angular/flex-layout" has an incompatible peer dependency to "rxjs" (requires "^5.5.0, would install "6.2.0").
Incompatible peer dependencies found. See above.
PS F:\Nick\Angular\firebase-work> npm view rxjs version
6.2.0
PS F:\Nick\Angular\firebase-work> npm view rxjs -g version
6.2.0
F:\Nick\Angular\firebase-work>
答案 3 :(得分：1)
问题出现在第二个while-loop中。 play变量应声明为char而不是int。另外，您不需要将其与Y和Q整数变量进行比较。这是一个解决方案。我跳它会帮助你：
#include <iostream>
#include <cstdio>
#include <time.h>
#include <stdlib.h>
using namespace std;
int main()
{
bool loop = true;
while (loop)
{
// Generate two random single-digit integers btwn 0-9
srand(time(0));
int num1 = rand() % 10;
int num2 = rand() % 10;
int operation, play, num3, guess, Y, Q;
// If num1 < num2, swap num1 with num2
if (num1 < num2)
{
int temp = num1;
num1 = num2;
num2 = temp;
}
cout << "Choose an operation.\n\t-----------------------" << endl;
cout << "\tEnter 1 to add,\n\tEnter 2 to subtract, or\n\tEnter 3 to multiply\n\t-----------------------\n\t\tEnter: ";
cin >> operation;
if (operation > 3 || operation < 1)
{
cout << "Invalid choice! Please try again." << endl;
continue;
}
else if (operation == 1)
{
cout << "You chose addition." << endl;
num3 = num1 + num2;
cout << "What is " << num1 << " + " << num2 << " = ";
cin >> guess;
if (guess != num3)
{
cout << "That is incorrect. Please try again." << endl;
cout << "What is " << num1 << " + " << num2 << " = ";
cin >> guess;
}
else if (guess == num3)
cout << "That is correct!" << endl;
}
else if (operation == 2)
{
cout << "You chose subtraction." << endl;
num3 = num1 + num2;
cout << "What is " << num1 << " - " << num2 << " = ";
cin >> guess;
if (guess != num3)
{
cout << "That is incorrect. Please try again." << endl;
cout << "What is " << num1 << " - " << num2 << " = ";
cin >> guess;
}
else if (guess == num3)
cout << "That is correct!" << endl;
}
else if (operation == 3)
{
cout << "You chose multiplication." << endl;
num3 = num1 * num2;
cout << "What is " << num1 << " * " << num2 << " = ";
cin >> guess;
if (guess != num3)
{
cout << "That is incorrect. Please try again." << endl;
cout << "What is " << num1 << " * " << num2 << " = ";
cin >> guess;
}
else if (guess == num3)
cout << "That is correct!" << endl;
}
while (true)
{
char play;
cout << "Would you like to play again? Press Y for yes or Q for quit: ";
cin >> play;
if (play == 'Y' || play == 'y')
break;
else if(play == 'Q' || play == 'q')
{
loop = false;
cout << "Good bye.\n";
break;
}
else
cout<< "Invalid choice.\n";
}
}
return 0;
}
使菜单有点互动也很好，和平。
答案 4 :(得分：0)
解决方案：
“编写一个让孩子练习算术技能的程序。
程序应首先询问需要什么样的练习：+， - ，*，并让用户根据需要多次重复练习，直到输入“Q”。
将从（0 - 9）生成两个随机数。
如果孩子正确回答等式，则应出现一条消息，然后他们可以转到下一个问题（生成两个不同的数字）。
如果孩子的答案不正确，则应显示一条消息＆amp;问题应该重复（使用相同的数字）。“
最后修好了！：
#include <iostream>
#include <cstdio>
#include <time.h>
#include <stdlib.h>
using namespace std;
int main()
{
int operation, num3, guess, num1, num2, temp;
char play;
srand(time(0));
do
{
num1 = rand() % 10;
num2 = rand() % 10;
if (num1 < num2)
{
temp = num1;
num1 = num2;
num2 = temp;
}
do
{
cout << "Choose an operation." << endl;
cout << "Enter 1 to add, 2 to subtract, or 3 to multiply: " << endl;
cout << "" << endl;
cin >> operation;
if (operation > 3 || operation < 1)
{
cout << "Your operation choice isn't valid! Please try again, using 1, 2, or 3." << endl;
}
}while (operation > 3 || operation < 1);
switch(operation)
{
case 1:
cout << "You chose addition." << endl;
num3 = num1 + num2;
cout << "" << endl;
do
{
cout << "What is " << num1 << " + " << num2 << " ?: " << endl;
cout << "" << endl;
cin >> guess;
cout << "" << endl;
if (guess != num3)
{
cout << "That is incorrect. Please try again." << endl;
cout << "" << endl;
}
} while (guess != num3);
if (guess == num3)
{
cout << "That is correct!" << endl;
cout << "" << endl;
}
break;
case 2:
cout << "You chose subtraction." << endl;
num3 = num1 - num2;
cout << "" << endl;
do
{
cout << "What is " << num1 << " - " << num2 << " ?: " << endl;
cout << "" << endl;
cin >> guess;
cout << "" << endl;
if (guess != num3)
{
cout << "That is incorrect. Please try again." << endl;
cout << "" << endl;
}
} while (guess != num3);
if (guess == num3)
{
cout << "That is correct!" << endl;
cout << "" << endl;
}
break;
case 3:
cout << "You chose multiplication." << endl;
num3 = num1 * num2;
cout << "" << endl;
do
{
cout << "What is " << num1 << " * " << num2 << " ?: " << endl;
cout << "" << endl;
cin >> guess;
cout << "" << endl;
if (guess != num3)
{
cout << "That is incorrect. Please try again." << endl;
cout << "" << endl;
}
} while (guess != num3);
if (guess == num3)
{
cout << "That is correct!" << endl;
cout << "" << endl;
}
break;
}
do
{
cout << "Would you like to play again? Press Y for yes or Q for quit" << endl;
cout << "" << endl;
cin >> play;
if (play != 'Y' && play != 'Q')
{
cout << "That is not a valid choice. Please choose Y for yes or Q to quit. " << endl;
cout << "" << endl;
}
}
while(play !='Y' && play !='Q');
if (play == 'Y')
{
cout << "Thank you for playing! Let's play again!" << endl;
cout << "" << endl;
}
else
{
cout << "Thank you for playing! See you next time!" << endl;
cout << "" << endl;
}
}
while(play=='Y');
return 0;
}