/in/foo.c: In function 'main':
/in/foo.c:9:2: warning: 'gets' is deprecated [-Wdeprecated-declarations]
  gets(ch);
  ^~~~
In file included from /in/foo.c:1:0:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
/in/foo.c:10:12: warning: implicit declaration of function 'strlen' [-Wimplicit-function-declaration]
  for(i=0;i<strlen(ch);i++){
            ^~~~~~
/in/foo.c:10:12: warning: incompatible implicit declaration of built-in function 'strlen'
/in/foo.c:10:12: note: include '<string.h>' or provide a declaration of 'strlen'
/in/foo.c:6:21: warning: variable 'c' set but not used [-Wunused-but-set-variable]
  char ch[10000]={0},c;
                     ^
/tmp/ccJVgFOG.o: In function `main':
foo.c:(.text.startup+0x4a): warning: the `gets' function is dangerous and should not be used.