breaking the loop

which function can i use in c/c++ so that as soon as i press a certain character then the loop breaks away goes into the next loop.
for example:
start:

Code:

for(..;..;..;) /*loop1*/
{....;
.....; /*now if i press any 'a' when loop 1 is excuting then it should go to loop 2
.....;
}
goto strat;
if(getch()=='a') /* loop 2*/
for (..;..;..)
...;
...;
..;