Compilare: user.cpp: In function ‘int main()’: user.cpp:13:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i<strlen(s)&&(!((s[i]>='a'&&s[i]<='z')||(s[i]>='A'&&s[i]<='Z')))) ^ user.cpp:19:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i<strlen(s)) ^ user.cpp:21:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i<strlen(s)&&((s[i]>='a'&&s[i]<='z')||(s[i]>='A'&&s[i]<='Z'))) ^ user.cpp:27:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(i<strlen(s)&&(!((s[i]>='a'&&s[i]<='z')||(s[i]>='A'&&s[i]<='Z')))) ^