View Compilation Error

0_0_32015320_24573.cpp: In function 'int main()':
0_0_32015320_24573.cpp:14:14: error: invalid conversion from 'int' to 'const char*' [-fpermissive]
   if(strlen(a)>=8&&strlen(a)<=16)
              ^
In file included from 0_0_32015320_24573.cpp:3:0:
GCC4.9.2/x86_64-w64-mingw32/include/string.h:54:18: note: initializing argument 1 of 'size_t strlen(const char*)'
   size_t __cdecl strlen(const char *_Str);
                  ^
0_0_32015320_24573.cpp:14:28: error: invalid conversion from 'int' to 'const char*' [-fpermissive]
   if(strlen(a)>=8&&strlen(a)<=16)
                            ^
In file included from 0_0_32015320_24573.cpp:3:0:
GCC4.9.2/x86_64-w64-mingw32/include/string.h:54:18: note: initializing argument 1 of 'size_t strlen(const char*)'
   size_t __cdecl strlen(const char *_Str);
                  ^