c++ - Throwing exceptions error 'terminate called...' -

okay, i've been following c++ guide, , got section on exception handling. couldn't of code work - produced variation on following error;

terminate called after throwing instance of 'char const*' 

where "char const*" type of whatever throwing.

i ctrl-c, ctrl-v 'ed example code guide, , ran see if error fault, or if there else going on. produced same error (above) code did.

here's code guide;

#include "math.h" // sqrt() function #include <iostream> using namespace std;  // modular square root function double mysqrt(double dx) {     // if user entered negative number, error condition     if (dx < 0.0)         throw "can not take sqrt of negative number"; // throw exception of type char*      return sqrt(dx); }  int main() {     cout << "enter number: ";     double dx;     cin >> dx;      try // exceptions occur within try block , route attached catch block(s)     {         cout << "the sqrt of " << dx << " " << mysqrt(dx) << endl;     }     catch (char* strexception) // catch exceptions of type char*     {         cerr << "error: " << strexception << endl;     } } 

always catch absolute const exceptions: catch (const char const* strexception).
it's neither intended, nor useful put changes (write operations) them. not on possible stack local copies.

though you're doing doesn't seem idea. convention exceptions these should implement std::exception interface, caught in canonical way. standard compliant way

class invalid_sqrt_param : public std::exception { public:      virtual const char* what() const {          return "can not take sqrt of negative number";      } }; 

---

double mysqrt(double dx) {     // if user entered negative number, error condition     if (dx < 0.0) {          // throw exception of type invalid_sqrt_param         throw invalid_sqrt_param();      }     return sqrt(dx); } 

---

// exceptions occur within try block  // , route attached catch block(s) try {     cout << "the sqrt of " << dx << " " << mysqrt(dx) << endl; } // catch exceptions of type 'const std::exception&' catch (const std::exception& ex) {     cerr << "error: " << ex.what() << endl; } 

note:
there's standard exception deigned case of invalid parameters passed function. alternatively can do

double mysqrt(double dx) {     // if user entered negative number, error condition     if (dx < 0.0) {          // throw exception of type invalid_sqrt_param         throw std::invalid_argument("mysqrt: can not take sqrt of negative number");      }     return sqrt(dx); }