Question 12.33

comp.lang.c FAQ list · Question 12.33

Q: How can I redirect stdin or stdout to a file from within a program?

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A: Use freopen. If you're calling a function f() which writes to stdout, and you want to send its output to a file, and you don't have the option of rewriting f, you can use a sequence like:

freopen(file, "w", stdout);
 f();

See, however, question 12.34.
References: ISO Sec. 7.9.5.4
H&S Sec. 15.2