關於C ++運算符的基本問題？

Question

我目前有這個代碼：

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

int main()
{
int a;
cout << "Enter a number for a: "; //Prompts the user for a and b inputs
cin >> a;

int b;
cout << "Enter a number for b: ";
cin >> b;

cout << "A is " << a << "\tB is " << b << end1;
cout <<"Sum of a and b is equal to " << a << "+" << b << "and the result is " << (a + b) << end1;
cout <<"Product of a and b is equal to " << a << "*" << b << "and the result is " << (a * b) << end1;
cout <<"a > b is " << a << ">" << b << "and the result is " << (a > b) << end1;
cout <<"a < b is " << a << ">" << b << "and the result is " << (a < b) << end1;
cout <<"a == b is " << a << "==" << b << "and the result is " << (a == b) << end1;
cout <<"a >= b is " << a << ">=" << b << "and the result is " << (a >= b) << end1;
cout <<"a <= b is " << a << "<=" << b << "and the result is " << (a <= b) << end1;
cout <<"a != b is " << a << "!=" << b << "and the result is " << (a != b) << end1;

return 0;
}

我收到這些錯誤

main.cpp: In function 'int main()':
main.cpp:10:44: error: 'end1' was not declared in this scope

我不確定我做錯了什么。

Answer 1

如上所述，編輯

• end1 - > endl （ 助記符：行尾 ）
• 刪除分號（分號結束語句，下一個語句將以<< ？ 開頭 ）
• 和括號子表達式（為了獲得優先權）

在科利魯看到它

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

int main()
{
    int a;
    cout << "Enter a number for a: "; //Prompts the user for a and b inputs
    cin >> a;
    int b;
    cout << "Enter a number for b: ";
    cin >> b;
    cout << "A is "                           << a << "\tB is " << b << endl
         << "Sum of a and b is equal to "     << a << "+"       << b << "and the result is " << (a + b) << endl
         << "Product of a and b is equal to " << a << "*"       << b << "and the result is " << (a * b) << endl
         << "a > b is "                       << a << ">"       << b << "and the result is " << (a > b) << endl
         << "a < b is "                       << a << ">"       << b << "and the result is " << (a < b) << endl
         << "a == b is "                      << a << "=="      << b << "and the result is " << (a == b) << endl
         << "a >= b is "                      << a << ">="      << b << "and the result is " << (a >= b) << endl
         << "a <= b is "                      << a << "<="      << b << "and the result is " << (a <= b) << endl
         << "a != b is "                      << a << "!="      << b << "and the result is " << (a != b) << endl;
    return 0;
}

輸出：

Enter a number for a: 3
Enter a number for b: 4
A is 3  B is 4
Sum of a and b is equal to 3+4and the result is 7
Product of a and b is equal to 3*4and the result is 12
a > b is 3>4and the result is 0
a < b is 3>4and the result is 1
a == b is 3==4and the result is 0
a >= b is 3>=4and the result is 0
a <= b is 3<=4and the result is 1
a != b is 3!=4and the result is 1

Answer 2

end1應該是endl否則會發生此錯誤。

該錯誤解釋了編譯器如何不知道end1是什么，例如在范圍中找不到。 它只是一個錯誤拼寫的endl ，它確實存在於范圍內。

此外，您需要在每行前面使用cout ，或者在最終輸出之前不要使用分號。

Answer 3

第一個錯誤是因為你使用end1 <--- number 1而不是endl <--- lowercase L.

剩下的錯誤是因為你用分號終止了那一行。 如果你想繼續輸出作為一個長表達式，不要在末尾使用分號。 可能更具可讀性的是在每個行的開頭使用cout。 像這樣：

cout <<“A is”<< a <<“\\ tB is”<< b << endl; cout <<“a和b之和等於”<< a <<“+”<< b << <<“，結果是”<< a + b << endl; cout <<“a和b的乘積等於”<< a <<“*”<< b << <<“，結果是”<< a * b << endl;

Answer 4

你有; 在行尾，但開頭沒有cout 。 一旦你到達了; 在行尾，它是一個新的語句，並且編譯器不知道如何處理類似<<"a > b is " << a << ">" ，因為至少應該有東西的左<< -和任何上的左，右<<也應該是可以接受的運營商<< 。

通過在相關位置的<<前面添加cout來修復它 - 或者通過刪除它使其成為一個非常長的行; - 但如果你有一個endl ，那么你也可以開始一個新的cout線。

[正如其他人所指出的那樣， endl與end1 ]

Answer 5

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

int main()
{
   int a;
   cout << "Enter a number for a: "; //Prompts the user for a and b   inputs
   cin >> a;

   int b;
   cout << "Enter a number for b: ";
   cin >> b;

   cout << "A is " << a << "\tB is " << b << endl;
   cout <<"Sum of a and b is equal to " << a << "+" << b << "and the   result is " << (a + b) << endl;
   cout <<"Product of a and b is equal to " << a << "*" << b << "and  the result is " << (a * b) << endl;
   cout <<"a > b is " << a << ">" << b << "and the result is " << (a > b) <<  endl;
   cout <<"a < b is " << a << ">" << b << "and the result is " << (a < b) << endl;
   cout <<"a == b is " << a << "==" << b << "and the result is " << (a == b) << endl;
   cout <<"a >= b is " << a << ">=" << b << "and the result is " << (a >= b) << endl;
   cout <<"a <= b is " << a << "<=" << b << "and the result is " << (a <= b) << endl;
   cout <<"a != b is " << a << "!=" << b << "and the result is " << (a != b) << endl;

   return 0;
}

你寫了'end1'代表新行.bt正確的關鍵字是'endl'（行尾）。解決方案在上面......

Answer 6

這是解決方案....

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

int main()
{
   int a;
   cout << "Enter a number for a: "; //Prompts the user for a and b   inputs
   cin >> a;

   int b;
   cout << "Enter a number for b: ";
   cin >> b;

   cout << "A is " << a << "\tB is " << b << endl;
   cout <<"Sum of a and b is equal to " << a << "+" << b << "and the   result is " << (a + b) << endl;
   cout <<"Product of a and b is equal to " << a << "*" << b << "and  the result is " << (a * b) << endl;
   cout <<"a > b is " << a << ">" << b << "and the result is " << (a > b) <<  endl;
   cout <<"a < b is " << a << ">" << b << "and the result is " << (a < b) << endl;
   cout <<"a == b is " << a << "==" << b << "and the result is " << (a == b) << endl;
   cout <<"a >= b is " << a << ">=" << b << "and the result is " << (a >= b) << endl;
   cout <<"a <= b is " << a << "<=" << b << "and the result is " << (a <= b) << endl;
   cout <<"a != b is " << a << "!=" << b << "and the result is " << (a != b) << endl;

   return 0;
}

Answer 7

首先，它是endl而不是end1 （最后一個char是L而不是1）

其次，你必須把cout放在每一行的前面，這一行以<<運算符開頭。 然后它會工作。