Programming :: Check If The Content Of A File Is "1"?

i want to close the program if the content of the file /tmp/file_name is 1 (just the number 1).

dont need to check all the time, just when start the program.

something like this:

Code:
"read the /tmp/file_name"
"check if the content of the file_name is 1"
"if not, do something"

what i need is very simple to do in shell script:

Code:
go=`cat /tmp/file_test` # "cat /tmp/file_test" read the content of the file_test
if [ "$go" -eq "1" ]; then # if the content of the file_test is 1
echo "ok, ready to exit now"; # now i can put the exit command
fi

but i dont know how to do the same thing in C...