/in/ex1.c: In function 'main':
/in/ex1.c:10:5: error: 'argc' undeclared (first use in this function)
     argc = argc + 0;
     ^~~~
/in/ex1.c:10:5: note: each undeclared identifier is reported only once for each function it appears in
/in/ex1.c:17:37: error: passing argument 1 of 'get_filename_ext' makes pointer from integer without a cast [-Werror=int-conversion]
         Filename = get_filename_ext(Filename);
                                     ^~~~~~~~
/in/ex1.c:4:13: note: expected 'const char *' but argument is of type 'char'
 const char* get_filename_ext(const char *filename) {
             ^~~~~~~~~~~~~~~~
/in/ex1.c:17:18: error: assignment makes integer from pointer without a cast [-Werror=int-conversion]
         Filename = get_filename_ext(Filename);
                  ^
/in/ex1.c:18:20: error: conversion to 'char' from 'int' may alter its value [-Werror=conversion]
         Filename = tolower(Filename);
                    ^~~~~~~
/in/ex1.c:24:10: error: 'i' undeclared (first use in this function)
     for (i = 0, i < Fcount, i++){
          ^
/in/ex1.c:24:15: error: left-hand operand of comma expression has no effect [-Werror=unused-value]
     for (i = 0, i < Fcount, i++){
               ^
/in/ex1.c:24:27: error: left-hand operand of comma expression has no effect [-Werror=unused-value]
     for (i = 0, i < Fcount, i++){
                           ^
/in/ex1.c:24:32: error: expected ';' before ')' token
     for (i = 0, i < Fcount, i++){
                                ^
/in/ex1.c:24:32: error: expected expression before ')' token
/in/ex1.c:12:10: error: variable 'file' set but not used [-Werror=unused-but-set-variable]
     char file[501] = {0};
          ^~~~
/in/ex1.c:11:9: error: unused variable 'Maxcount' [-Werror=unused-variable]
     int Maxcount = 0;
         ^~~~~~~~
cc1: all warnings being treated as errors