how can get other process pid

[walker]

hi, I want to get other process pid in my program. the other process
name is known, I want get its pid, how can I do?

for example : in my program I call a process named "mpg321" to play a
mp3 file , now I want to stop it by kill it a STOP signal,to do this, I
must know the pid of mpg321 which is running, how can I get its pid ?

any of you help will be appreciated!

walker