As in the miniunz.c
file from Zip Code.
The function definition is as follows:
int makedir (newdir)
char *newdir;
So by considering that, There are two ways to do this.
char* write_filename;
fopen((char*)write_filename,"wb");
makedir(write_filename);
OR
const char* write_filename;
fopen(write_filename,"wb");
makedir((char*)write_filename);
Or Check your makedir()
function.
Hope this will help you.