Loop

[Hansikk]

So i'm back

How can i make a loop in my program?
http://pastebin.com/ZMmTP6Lz
anyone willing to help me?

i want like

int main()
{
start
{
body
}
cout << "again?";
cin >> answer;
if (answer == 1)
{
goto START
}
else
{
return 0;
}
}

[hanst99]

There are 3 different loop types in C++ (excluding the goto thingy):

while(condition)
{
//repeat this stuff
}

do
{
//repeat this stuff
} while (condition);

for(/*do this before first iteration*/;
/*if this is true, perform iteration*/;
/*do this after each iteration*/)
{
//repeat this stuff
}

//examples
int i = 0;
while(i<10)
{
++i;
cout<<i;
}

int i = 0;
do
{
++i;
cout<<i;
} while (i<10);

for(int i=0; i<10; ++i)
{
cout<<i;
}

The examples all pretty much do the same exact thing.

[Gaminic]

Small related question: In many situations, whiles and fors are interchangeable. If that's the case, is there a "best option", efficiency-wise?

[hanst99]

Nope, not really. And you shouldn't worry about efficiency at those points, really. There are situations in which efficiency is important, but the difference between a for and a while loop is unlikely to be ever big enough to make it worth considering to make a decision between the two based on efficiency. Chances are your compiler implements the two exactly the same way anyways.

[NetMage]

Depending on the situation though, it may be easier or more clear to write a 'while' loop over a 'for' loop, vice versa. Example:

it may be easier to write a while loop if you want something to repeat in process WHILE some condition is true. It may be easier to write a for loop if there are only a set number of steps in the program. Just food for thought.

However, yes they are both pretty much always interchangeable.

[filipe]

A for loop is also executed while some condition is true.