有没有办法检查变量是否是整数？C++
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Is there a way to check if a variable is a whole number? C++
提问by Billjk
I need to check if a variable is a whole number, say I have the code:
我需要检查一个变量是否是一个整数，假设我有代码：
double foobar = 3;
//Pseudocode
if (foobar == whole)
cout << "It's whole";
else
cout << "Not whole";
How would I do this?
我该怎么做？
回答by laurent
Assuming foobaris in fact a floating point value, you could round it and compare that to the number itself:
假设foobar实际上是一个浮点值，您可以将其四舍五入并将其与数字本身进行比较：
if (floor(foobar) == foobar)
cout << "It's whole";
else
cout << "Not whole";
回答by Pepe
You are using int so it will always be a "whole" number. But in case you are using a double then you can do something like this
您使用的是 int 所以它总是一个“整数”。但是如果你使用的是 double 那么你可以做这样的事情
double foobar = something;
if(foobar == static_cast<int>(foobar))
return true;
else
return false;
回答by Asha
Depends on your definition of whole number. If you consider only 0 and above as whole number then it's as simple as: bool whole = foobar >= 0;.
取决于你对整数的定义。如果你只考虑0以上的整数那么它的那样简单：bool whole = foobar >= 0;。
回答by Rohit Vipin Mathews
just write a functionor expressionto Check for whole number, returning bool.
只需写一个functionorexpression到 Check for whole number，返回bool。
in usual definition i think whole number is greater than 0 with no decimal part.
在通常的定义中，我认为整数大于 0，没有小数部分。
then,
然后，
if (abs(floor(foobar) )== foobar)
cout << "It's whole";
else
cout << "Not whole";
回答by Moia
A concise version of Pepe's answer
Pepe 答案的简明版本
bool isWhole(double num)
{
return num == static_cast<int>(num);
}
