/in/foo.c: In function 'str_replace':
/in/foo.c:6:6: warning: unused variable 'i' [-Wunused-variable]
  int i;
      ^
/in/foo.c: In function 'main':
/in/foo.c:40:5: warning: 'gets' is deprecated [-Wdeprecated-declarations]
     gets(str1);
     ^~~~
In file included from /in/foo.c:2:0:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
/in/foo.c:41:5: warning: 'gets' is deprecated [-Wdeprecated-declarations]
     gets(str2);
     ^~~~
In file included from /in/foo.c:2:0:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
/in/foo.c:42:5: warning: 'gets' is deprecated [-Wdeprecated-declarations]
     gets(str3); 
     ^~~~
In file included from /in/foo.c:2:0:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
/in/foo.c:38:10: warning: unused variable 'c' [-Wunused-variable]
     char c;
          ^
/in/foo.c:37:11: warning: unused variable 'len' [-Wunused-variable]
     int i,len,count=0;
           ^~~
/in/foo.c:37:9: warning: unused variable 'i' [-Wunused-variable]
     int i,len,count=0;
         ^
/tmp/ccJsp92H.o: In function `main':
foo.c:(.text.startup+0x24): warning: the `gets' function is dangerous and should not be used.