Compilare: user.cpp: In function ‘int main()’: user.cpp:50:23: warning: suggest parentheses around ‘&&’ within ‘||’ [-Wparentheses] if((s[i]<='9')&&(s[i]>='0')||(s[i]<='z')&&(s[i]>='a')) ^ user.cpp:58:9: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] s[j]=NULL; ^ user.cpp:20:26: warning: unused variable ‘aux’ [-Wunused-variable] char s[1001],cuv[21],aux[21]; ^ user.cpp:21:42: warning: unused variable ‘b’ [-Wunused-variable] int a,cant[100],i=0,n,t=0,q=0,j,c,ok,b; ^