Compilare: user.cpp: In function ‘void build_prefix1()’: user.cpp:20:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 1; i < a.length(); i++) ^ user.cpp:38:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < a.length(); i++) ^ user.cpp: In function ‘void build_prefix2()’: user.cpp:46:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 1; i < b.length(); i++) ^ user.cpp:52:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 2; i <= b.length()-1; i++) ^ user.cpp:64:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < b.length(); i++) ^ user.cpp: In function ‘int main()’: user.cpp:123:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(k == (b.size() - 1)) ^ user.cpp:132:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i = 0; i < indexA.size(); i++) ^ user.cpp:134:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(j < indexB.size() && (indexA[i] + n > indexB[j] || (indexB[j] - (b.length() - 1) + 1) < indexA[i] )) ^ user.cpp:134:115: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(j < indexB.size() && (indexA[i] + n > indexB[j] || (indexB[j] - (b.length() - 1) + 1) < indexA[i] )) ^