How to know if a package is installed in Linux using C

Question

I am creating an alarm clock for my project in C. I am using mgp123 command(in package mpg321) to run the alarm sound. It is only for UBUNTU users.I need the program to check whether mpg321 is installed or not. How can i find using C if the package mpg321 is installed using C program?

Answer 1

you can use system()

system("mpg321 -h");

if the command return error than the mpg321 is not installed