如何在 cpp 中检查给定输入的数据类型？

Question

如果我给出 10 意味着它应该打印它是一个整数 如果我给出 10.2 意味着它应该打印它是一个浮点 如果我给出 'a' 意味着它应该打印它是一个字符

Answer 1

Read the input as a std::string first.

Then, pass the string to std::stoi() , and if it consumes the whole string without error, print the resulting integer.

Otherwise, pass the string to std::stof() , and if it consumes the whole string without error, print the resulting float.

Otherwise, print the string as-is.

Answer 2

You can use type_traits and template specialization to achieve this. Please see this example for more info:-

#include <iostream>
#include <type_traits>

template<typename T>
struct is_integer{
    static const bool value = false;
};

template<>
struct is_integer<int>{
    static const bool value = true;
};

template<typename T>
struct is_char{
    static const bool value = false;
};

template<>
struct is_char<char>{
    static const bool value = true;
};

template<typename T>
void printType(T t){
    if(is_integer<T>::value)
    {
        std::cout<<"Value is integer"<<std::endl;
    }
    else if(is_char<T>::value)
    {
        std::cout<<"Value is char"<<std::endl;
    }
    else if(std::is_floating_point<T>::value)
    {
        std::cout<<"Value is float"<<std::endl;
    }
}

int main()
{
    int i = 10;
    char j = 'a';
    float k = 10.2f;

    printType(i);
    printType(j);
    printType(k);

    return 0;
}