concat.cpp: In function `int valid_val(int)': concat.cpp:24: warning: comparison between signed and unsigned integer expressions concat.cpp:27: warning: comparison between signed and unsigned integer expressions concat.cpp:26: warning: unused variable `int ok' concat.cpp: In function `void back(int)': concat.cpp:37: warning: unused variable `char temp[201]' concat.cpp:38: warning: unused variable `int rez' /tmp/cc8KdEv9.o(.text+0x25b): In function `main': : the `gets' function is dangerous and should not be used.