Compilare: user.cpp: In function ‘void makeprefix()’: user.cpp:10:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=2; i<pattern.length(); ++i) { ^ user.cpp: In function ‘int main()’: user.cpp:28:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=1; i<text.length(); ++i) { ^ user.cpp:32:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (k==pattern.length()-1) { ^