I'm new to arduino and i am having difficulty with running the codes.
Here's the error message. What's causing the codes not to work?
Arduino: 1.6.11 (Windows 10), Board: "Arduino/Genuino Uno"
Build options changed, rebuilding all
C:\Users\EullaAirra\Desktop\Breathalizer_with_GSM\Breathalizer_with_GSM.ino:14:20: fatal error: SIM900.h: No such file or directory
#include "SIM900.h"
^
compilation terminated.
exit status 1
Error compiling for board Arduino/Genuino Uno.
Try
#include <SIM900.h>
-jim lee
How to know if i installed that library?
This is my codes 
codes.txt (9.21 KB)
xprimrose:
How to know if i installed that library?
I'm very sorry you're getting so much unhelpful hot air about this.
Here's how you check what libraries are already installed:
Look in Library Manager in the IDE. (Sketch -> Include Library -> Manage Libraries)
If you change Type to "Installed" you can see a list of what libraries are installed.
I'm very sorry you're getting so much unhelpful hot air about this.
Well, I'm not a contributor to the air mass, but I'm not sorry to see people ask VERY reasonable questions. OP is the one providing the stupid answers. OP deserves the abuse that results.