Compilare: user.cpp: In function ‘int main()’: user.cpp:32:51: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(p->v[w[i]-'a']!=NULL&&i<strlen(w)){p=p->v[w[i]-'a'];i++;} ^ user.cpp:33:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=i;j<strlen(w);j++){p->nr++;p->v[w[j]-'a']=new trie;p->v[w[j]-'a']->tata=p;p->v[w[j]-'a']->x=0;p=p->v[w[j]-'a'];} ^ user.cpp:42:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i<strlen(w)){p=p->v[w[i]-'a'];i++;} ^ user.cpp:67:59: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(p->v[w[i]-'a']!=NULL&&i<strlen(w)){p=p->v[w[i]-'a'];i++;} ^ user.cpp:68:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(i==strlen(w))g<<p->x<<'\n'; ^ user.cpp:75:59: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(p->v[w[i]-'a']!=NULL&&i<strlen(w)){p=p->v[w[i]-'a'];i++;} ^