add some more math operations.

c/mul/main.c

#include <math.h>
#include <stdio.h>
#include <editline/readline.h>
	if (strcmp(op, "-") == 0) { return x - y; }
	if (strcmp(op, "*") == 0) { return x * y; }
	if (strcmp(op, "/") == 0) { return x / y; }
	if (strcmp(op, "%") == 0) { return x % y; }
	if (strcmp(op, "^") == 0) { return pow(x, y); }
	if (strcmp(op, "min") == 0) { return x < y ? x : y; }
	if (strcmp(op, "max") == 0) { return x > y ? x : y; }
	return 0;
}
	mpca_lang(MPC_LANG_DEFAULT,
		"\
number   : /-?[0-9]+(\\.[0-9]+)?/ ; \
operator : '+' | '-' | '*' | '/' | /[a-zA-Z-]+/ ; \
operator : '+' | '-' | '*' | '/' | '%' | '^' | /[a-zA-Z-]+/ ; \
expr     : <number> | '(' <operator> <expr>+ ')' ; \
lang     : /^/ <expr>+ /$/ ; \
",