foo.cc: In function 'int main()':
foo.cc:45:29: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
   45 |         char exp[10005];gets(exp);
      |                         ~~~~^~~~~
In file included from /nix/store/1x1q5sqa0ilbi8fz7aayk02pjy5g7jhh-gcc-12.3.0/include/c++/12.3.0/cstdio:42,
                 from stdc++.h:46:
/nix/store/3w4yrspgcx1z9wi18rv0hbap4jjlhx4c-glibc-2.37-8-dev/include/stdio.h:605:14: note: declared here
  605 | extern char *gets (char *__s) __wur __attribute_deprecated__;
      |              ^~~~
foo.cc: In function 'double Cal(double, char, double)':
foo.cc:10:1: warning: control reaches end of non-void function [-Wreturn-type]
   10 | }
      | ^
/nix/store/j2gmfdd29cp3rcvghmn1a5kgcnmf8myp-binutils-2.40/bin/ld: /tmp/cc30HEbN.o: in function `main':
foo.cc:(.text.startup+0xf): warning: the `gets' function is dangerous and should not be used.

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