Compilare: user.cpp: In function ‘int paranteza(char*)’: user.cpp:22:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<strlen(s)-1;++i) ^ user.cpp:30:33: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses] if(st[top]=='(' && s[i]==')' || st[top]=='[' && s[i]==']') ^ user.cpp: In function ‘void citire(char*)’: user.cpp:52:15: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] s[++i]=NULL; ^ user.cpp: In function ‘int pop()’: user.cpp:18:1: warning: control reaches end of non-void function [-Wreturn-type] } ^