Compilare: main.c: In function 'query': main.c:120:4: warning: 'return' with no value, in function returning non-void return; ^~~~~~ main.c:116:5: note: declared here int query(TrieNode *node, char *s) { ^~~~~ main.c: In function 'main': main.c:172:11: warning: implicit declaration of function 'read' [-Wimplicit-function-declaration] iindex = read(0, input, 2000000); ^~~~ main.c:198:2: warning: implicit declaration of function 'write' [-Wimplicit-function-declaration] write(1, output, oindex); ^~~~~ main.c:162:17: warning: unused variable 'buf' [-Wunused-variable] char line[32], buf[32]; ^~~ main.c:162:7: warning: unused variable 'line' [-Wunused-variable] char line[32], buf[32]; ^~~~ main.c:166:5: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen( "trie.in", "r", stdin ); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:167:2: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen( "trie.out", "w", stdout ); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~