判断输入数值是否包含小数点

#include <iostream>
#include <string>
#include <sstream>


using namespace std;

int main(){
    double num;
    stringstream  s;
    char str[512];
    char c[512];
    //cout.setf(ios_base::fixed, ios_base::floatfield); fixed-float
    cout<<"Input a number: ";
    cin >>num;
    s << num;
    s >> str;
    sscanf(str,"%[0-9]",c);
    if(strlen(str)!=strlen(c))
    cout<<num<<" is a decimal number"<<endl;
    else
    cout<<num<<" is an integral number"<<endl;
    return 0;
}