Compilare: user.cpp: In function ‘int main()’: user.cpp:13:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0;i<strlen(s);i++) ^ user.cpp:51:51: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(s[i]>='0'&&s[i]<='9'&&i<strlen(s)) {a[k]=a[k]*10+s[i]-'0'; i++;} ^ user.cpp:60:56: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] i++; while(s[i]>='0'&&s[i]<='9'&&i<strlen(s)) {a[k]=a[k]*10+s[i]-'0'; i++;} ^