Compilare: user.c: In function ‘set_insert’: user.c:109:3: warning: implicit declaration of function ‘malloc’ [-Wimplicit-function-declaration] (*root) = malloc(sizeof(set_node)); //Allocating size for the set ^ user.c:109:13: warning: incompatible implicit declaration of built-in function ‘malloc’ [enabled by default] (*root) = malloc(sizeof(set_node)); //Allocating size for the set ^ user.c:136:7: warning: incompatible implicit declaration of built-in function ‘malloc’ [enabled by default] x = malloc(sizeof(set_node)); ^ user.c: In function ‘set_search’: user.c:243:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ user.c: In function ‘main’: user.c:277:8: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in,"%d", &n); ^ user.c:283:9: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in,"%d", &el); ^