Styjun

I've overloaded an operator such that I can return the value of an array. I can handle out of bounds using if:

float arr::operator[](const int i) const

 if (i < 0)
 
 cout << "Outside of array, first entry returned" << endl;
 return value[0];
 

 else if (i >=size)
 
 cout << "Outside of array, last entry returned" << endl;
 return value[size-1];
 

 else return value[i];

but I am learning about exceptions and try-catch blocks.

Is it possible to throw an exception with a different int (for example) for out of upper/lower bounds, and have catches that execute different code depending on the value of that int?

I know that if works well here, but I'm looking to develop my knowledge for use in more complex ideas.

Is it possible to throw an exception with a different int (for example) for out of upper/lower bounds, and have catches that execute different code depending on the value of that int?

Sort of. You can certainly throw a different int value based on a condition, but you would have to catch a single generic int and test its value, you can't catch different int values individually. For example:

const int OutOfBoundsInFront = -1;
const int OutOfBoundsInBack = 1;

float arr::operator[](const int i) const

 if (i < 0)
 throw OutOfBoundsInFront;

 if (i >= size)
 throw OutOfBoundsInBack;

 return value[i];


...

try

 ... = myarr[index];

catch (int value)

 switch (value)
 
 case OutOfBoundsInFront:
 //...
 break;

 case OutOfBoundsInBack:
 //...
 break;
 

However, when throwing an exception, it is better to throw an object instead of a simple POD type. catch blocks deal in types, not values. In this case, you can define different class types for each condition you want to catch. For example:

#include <stdexcept>

class OutOfBoundsInFront : public std::out_of_range

public:
 OutOfBoundsInFront() : std::out_of_range("out of bounds in front") 
;

class OutOfBoundsInBack : public std::out_of_range

public:
 OutOfBoundsInBack() : std::out_of_range("out of bounds in back") 
;

float arr::operator[](const int i) const

 if (i < 0)
 throw OutOfBoundsInFront();

 if (i >= size)
 throw OutOfBoundsInBack();

 return value[i];


...

try

 ... = myarr[index];

catch (const OutOfBoundsInFront &)

 //...

catch (const OutOfBoundsInBack &)

 //...

Alternatively:

#include <stdexcept>

class OutOfBoundsOnSide : public std::out_of_range

public:
 enum WhichSide InFront, InBack ;

 static const char* WhichSideErrorMsg[] = 
 "out of bounds in front",
 "out of bounds in back"
 ;

 WhichSide whichSide;

 OutOfBoundsOnSide(WhichSide side) : std::out_of_range(WhichSideErrorMsg[side]), whichSide(side) 
;

class OutOfBoundsInFront : public OutOfBoundsOnSide

public
 OutOfBoundsInFront() : OutOfBoundsOnSide(InFront) 
;

class OutOfBoundsInBack : public OutOfBoundsOnSide

public
 OutOfBoundsInBack() : OutOfBoundsOnSide(InBack) 
;

float arr::operator[](const int i) const

 if (i < 0)
 throw OutOfBoundsInFront();

 if (i >= size)
 throw OutOfBoundsInBack();

 return value[i];


...

try

 ... = myarr[index];

catch (const OutOfBoundsOnSide &e)

 switch (e.whichSide)
 
 case InFront:
 //...
 break;

 case InBack:
 //...
 break;