$_ = "hint int stint";
s/(int)/$1$1$1/g;
print;

##</code><code>##

hintintint intintint stintintint

##</code><code>##

$_ = "hint int stint";
s/int/$&$&$&/g;
print;

##</code><code>##

$_ = "hint int stint";
s/\b(int)\b/$1$1$1/g;
print;

##</code><code>##

hint intintint stint