When does printf fail to print?

Question

printf function in c doesn\'t always print the output on screen. For example if you forget to put \\n at the end of string you are printfing you sometimes don\'t get the o/p

Answer 1

There is another special case I just encountered:

My variables are:

line="-24 hours"
line2="24 hours"

and try

printf $line 
printf $line2

Neither will work. The second one drops the word "hours" and the first one mistakes -24 as a flag.

Therefore, whenever I use printf I will remove all the dangerous characters if possible, by using

sed -r "s/[/\ #;&~]/_/g"

I wish printf's codes can be improved by the developer.

Take care