Custom exception handling can not run in Ubuntu but Dev C can - c++

Question

When i use this code bellow: exception error is not print out screen when I using g++ in Ubuntu but when i change to Dev C in C++.
#include <iostream>
#include <exception>
#include <stdexcept>
#include <string.h>
#include <sstream>
#include <cmath>
#include <stdio.h>
#include <stdlib.h>
using namespace std;
//Define Class for exception error
class NoBinaryNumber: public logic_error{
private:
string s;
int x;
public:
NoBinaryNumber(string msg,int x) : logic_error(msg){
s = msg; this->x=x;
}
const char* what() const throw(){
ostringstream a;
a.str("");
a << s << " is wrong at position "<< x;
if(a)
return a.str().c_str();
else
return "";
}
~NoBinaryNumber() throw(){};
};
class BinaryStringToNumber{
public:
int number;
BinaryStringToNumber(string s){
number=0;
for (int i=s.length()-1;i>=0;i--){
if ((s[i]=='1')||(s[i]=='0')){
number=number+(s[i]-'0')*pow(2,i);
}
else{
throw NoBinaryNumber(s,s.length()-i);
cout << "alala" ;
}
}
}
};
int main(){
//Using customer exception error
try{
BinaryStringToNumber a("2");
cout << a.number << endl;
}
catch (NoBinaryNumber& e){
cout << e.what() << endl;
}
return 0;
}
The result shoud be: "2 is wrong at position 1"

Answer 1

In your what() function, you are creating an object (ostringstream), which is destructed at the end of this function call, and trying to access its content (a.str().c_str()) outside of what() function. This is an undefined behaviour (UB) and the fact that DevC++ is showing is just because it is an UB.
To solve this, I suggest you to create your message at constructor call and use what() just to show this message. Something like this:
class NoBinaryNumber: public logic_error{
private:
string s;
int x;
public:
NoBinaryNumber(string msg,int x) : logic_error(msg){
s = msg + " is wrong at position " << std::to_string(x);
this->x=x;
}
const char* what() const throw(){
return msg.c_str();
}
};