added the gpio_export function

main.c

@@ -1,18 +1,23 @@
+// Ignacio Abundez Ortega
+// gpio command tool
+
 #include <stdio.h>
 #include <fcntl.h>
 #include <unistd.h>
+#include <string.h>
+
+//prototype functions
+
+int gpio_export(const char *gpio);
+int gpio_direction(int gpio, const char *direction);
+int gpio_write(int gpio, int value);
 
 int main (int argc, char *argv[]){
+
 	int fd;
-	// export 
-	fd = open("/sys/class/gpio/chip0/export", O_WRONLY);
-	if (fd < 0){
-		perror("Error opening the GPIO path");
-		return -1;
-	}
-	write(fd,"17", 2);
-	close(fd);
+	char pin[] = "17";
 
+	gpio_export(pin);	
 	//pin direction
 	fd = open("/sys/class/gpio/chip0/gpio17/direction", O_WRONLY);
 	if (fd < 0){
@@ -61,4 +66,20 @@ int main (int argc, char *argv[]){
 	return 0;
 }
 
+//Complete functions
+//
+//gpio_export
 
+int gpio_export(const char *gpio){
+	
+	int fd; 
+	 
+	fd = open("/sys/class/gpio/chip0/export", O_WRONLY);
+	if (fd < 0){
+		perror("Error opening the GPIO path");
+		return -1;
+	}
+	write(fd,gpio, strlen(gpio));
+	close(fd);
+	return(0);
+}