C ++如何比较2个整数以查看它们是否相等？一个是用户输入，另一个是结构的一部分？
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C++ How to compare 2 integers to see if they are equal? One is user input and the other is part of a struct?
提问by Amy
I have an user input ID (which is int) and then I have a Contact ID that is part of my Struct. The Contact ID is int also.
我有一个用户输入 ID（它是 int），然后我有一个 Contact ID，它是我的 Struct 的一部分。联系人 ID 也是 int。
I need to compare to see if they are the same, if they are, then I know that it exists.
我需要比较看看它们是否相同，如果它们相同，那么我知道它存在。
This is the closest thing I found but it is not working: http://www.cplusplus.com/reference/string/string/compare/
这是我发现的最接近的东西，但它不起作用：http: //www.cplusplus.com/reference/string/string/compare/
From reading that page, I did something like:
通过阅读该页面，我做了类似的事情：
if(user_input_id.compare(p->id)==0)
{
}
I get error message saying that expression must have class type.
我收到错误消息，指出表达式必须具有类类型。
How do I compare two integers in C++?
如何在 C++ 中比较两个整数？
回答by Joseph Mansfield
The function you found is for comparing two std::strings. You don't have std::strings, you have ints. To test if two ints are equal, you just use ==like so:
您找到的函数用于比较两个std::strings。你没有std::strings，你有ints。要测试两个ints 是否相等，您只需==像这样使用：
if (user_input_id == p->id) {
// ...
}
In fact, even if you had two std::strings, you'd most likely want to use ==there too.
事实上，即使你有两个std::strings，你也很可能想在==那里使用。
回答by xis
I am unsure what you mean, but IMHO
我不确定你的意思，但恕我直言
int k;
std::cin>>k;
if (k==p->id)
do_sth();
else
do_sth_else();
The point is you do not store input as string, but a int.
关键是您不将输入存储为字符串，而是一个 int。
回答by Cereal_Killer
//simple program to compare
#include<iostream>
using namespace std;
typedef struct node {
int a;
}node;
int main() {
node p;
p.a = 5;
int a;
cin >> a;
if( p.a == a )
cout << "Equal" << endl;
else
cout << "Not Equal"<< endl;
return 0;
}
回答by muneebahmad
IF your struct's name is p and you have an integer in it called hello, you can do the following
如果您的结构名称是 p 并且您在其中有一个名为 hello 的整数，则可以执行以下操作
int input;
cin << input;
if(input == p.hello){
cout << "the input is equal to p.hello" << endl;
}
else{
cout << "the input is not equal to p.hello" << endl;
}
