Compilare: user.cpp: In function ‘void fis()’: user.cpp:9:23: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses] for(i=poz; s[i]>='a' && s[i]<='z' || s[i]<='9' && s[i]>='0'; i++) nf[i-poz]=s[i]; ^ user.cpp:10:11: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] nf[i-poz]=NULL; ^ user.cpp: In function ‘void dir()’: user.cpp:19:4: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] *p=NULL; ^