How to convert gchar to char in C language?

["Mee Com" <writemessage hotmail com>]

In gtk+2.0 the variable for character is "gchar",
so if my code include file which write in C Language ,
that use the type of character is "char" or "unsigned char"
such as char a;
how do I change the format of gchar to char? or how do I change format of 
char to gchar?
that I can recieve input from the file which I included.
For example, I want to include the file write_in_C_language.c which has char 
a;
how do I recieve the value from char a to my application which write with 
GTK. that in my GTK file use gcha,such as gchar x;?
                when I use gchar x = a;
               when compiled,it said incorrect formatted data type,that I 
knew it,but how do I solve this problem?
Thanks for all of your advise!
Regards,

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