Compilare: main.cpp: In function 'void add_word(node*, int)': main.cpp:30:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(ind == s.size()) {node->words++;return;} ~~~~^~~~~~~~~~~ main.cpp: In function 'void remove_word(node*, int)': main.cpp:47:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(ind < s.size()) ~~~~^~~~~~~~~~ main.cpp: In function 'int word_frequency(node*, int)': main.cpp:65:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(ind == s.size()) return node->words; ~~~~^~~~~~~~~~~ main.cpp: In function 'int common_prefix(node*, int)': main.cpp:78:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(ind == s.size()) return ind; ~~~~^~~~~~~~~~~ main.cpp: In function 'void remove_word(node*, int)': main.cpp:54:36: warning: 'letter' may be used uninitialized in this function [-Wmaybe-uninitialized] if(del==1) node->nodes[letter] = NULL; ^