If a and a are both null-terminated strings, then you have to call strcmp() to check of the two strings are the same. The following will produce a two-dimensional array of strings that contain up to 40 characters each.
if( strcmp(a, a) == 0)
printf("Both strings are the same\n");
isn't the code you need similar to the program you posted in this thread. If so if you imply my suggestion of using a 2d array for the variable on the code there then you'll have char array (string) values from user input