Compilare: user.cpp: In function ‘int main()’: user.cpp:17:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<strlen(s);++i) ^ user.cpp:21:66: warning: converting to non-pointer type ‘char’ from NULL [-Wconversion-null] else{while(x+3>L) {x-=len[(int)s[strlen(s)-1]];s[strlen(s)-1]=NULL;} ^ user.cpp:11:9: warning: unused variable ‘l’ [-Wunused-variable] int l[100],L,i,k=-1,x=0,len[300]; ^ user.cpp:11:20: warning: unused variable ‘k’ [-Wunused-variable] int l[100],L,i,k=-1,x=0,len[300]; ^