Compilare: user.cpp: In function ‘int main()’: user.cpp:138:42: warning: format ‘%d’ expects argument of type ‘int’, but argument 2 has type ‘long int’ [-Wformat=] printf("%d \n", treeEval(expressionTree)); ^ user.cpp: In function ‘long int treeEval(node*)’: user.cpp:54:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ user.cpp: In function ‘void readData()’: user.cpp:42:12: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(expr); ^ /tmp/cc3dcP8q.o: In function `main': user.cpp:(.text.startup+0x3b): warning: the `gets' function is dangerous and should not be used.