I am working on a C/C++ code, that one of the things it does is replacing a line that has the sentence UNIX_CODE_TOKEN=. I thought I would use system() in order to run sed -i .... Nevertheless, I have noticed that system() is not quite efficient. Thus, I have come to you for good suggestions.
Is there a C/C++ built in function that does the sed -i without using the system()?
Please don’t tell me to use fstream in C++ or the FILE * in C (also fseek and lseek won’t help because I want to replace a specific word in a line),
I decided not to write a function that does the replacement.
Thanks for any help/suggestion/reply.
system() is typically implemented in terms of fork() to split the process, exec() to launch /bin/sh (or whatever) in your child process, and waitpid() in the parent to block until the subshell completes. In your case, you will probably need to implement this yourself, but directly exec() /bin/sed rather than /bin/sh.
Implementing this correctly is a reasonable amount of work, however. Have you actually benchmarked and profiled your program to determine whether system() is even a performance problem? It’s much more likely that sed is slow – it’s having to access a slow disk, after all – and your investigations are incorrectly fingering system(). You’ll probably find that the fastest way is indeed to process the file directly within your program bit this won’t actually make it much faster overall anyway.
What is the higher-level problem you’re trying to solve? There’s a good chance that the need to edit a file can be removed completely.