How to use printf and bash I/O redirection

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C

Bash

My program runs very similar like "cat" command in shell
but I failed to print the messages to file when I try to use

dog Hello > inputfile

In my code , I only use printf to print the messages,
it works when the stdout is screen, but fails when I try to output to a file..

I think the bash will handle this auto, and since printf is to print msg to
stdout, and > in bash can change the stdout to the file, right ?~

Thanks ..