Re: Can throw-catch be used as substitute for goto?
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<artella.coding@googlemail.com> wrote in message
news:1190817506.505226.242800@o80g2000hse.googlegroups.com...
Hi,
I know that the following is not what throw and catch were designed to
do, but is it not possible to use throw and catch as an alternative to
goto?
For example in the code below, method 1 breaks out of the double for
loop using the goto, whilst method 2 breaks out of the double for loop
using throw and catch.
What are your thoughts on this? Thanks.
Code:
#include <iostream>
using namespace std;
const int asize = 5;
int main(void)
{
//Method 1 - using goto to exit double for loop
for(int row = 0; row < asize; ++row){
for(int col = 0; col < asize; ++col){
cout<<"row = "<<row<<", col = "<<col<<endl;
if(row==2 && col==2){
goto escape;
}
}
}
escape :
cout<<"Finished method 1\n";
//Method 2 - using throw and catch to exit double for loop
int escape=0;
try{
for(int row = 0; row < asize; ++row){
for(int col = 0; col < asize; ++col){
cout<<"row = "<<row<<", col = "<<col<<endl;
if(row==2 && col==2){
throw escape;
}
}
}
}catch(int){}
cout<<"Finished method 2\n";
system("pause");
return(0);
}
Hi
The practace that you are suggesting is not one that is recommended. Where
there is misuse of the language constructs, one is almost always bitten
when
the bight is unexpected. Although the practace of using exceptions for
flow
control MAY not cause problems in the logic of your program, it is
likely to
cause some degree of unnecessary inefficiency in the program.
Even though goto statements are generally frowned apon, I would suggest
using them for this situation, but if goto really makes you unconfortable,
you could use a boolean flag to indicate when the loops should exit, like
the following program:
#include <iostream>
int main()
{
using std::cout;
using std::cin;
cout << "Finding the 2 numbers, when multiplied equal 21.\n";
bool done = false;
for (int i = 1; i <= 10; ++i)
{
for (int j = 1; j <= 10; ++j)
{
int result = i * j;
if (result == 21)
{
done = true;
cout << "Found them! They are: " << i << " and " << j << "\n";
}
if (done)
{
break;
}
}
if (done)
{
break;
}
}
cin.get();
return 0;
}
If you use a boolean flag, do NOT use it as part of a condition in a for
loop, I tried it, and the result can be unexpected, just by looking at the
statement.
I hope this helps.
Paul
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