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Should I use roundf that is for float input and returns a float value? the function round seems to work equally well. Any views on this?

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roundf and other functions in the "round" family should be used wherever a float or double must be rounded, that includes both input (before any calculation is performed using it) or output (values that are the result of some calculation).

Beside that I'm not exactly sure what you're asking, you may want to check the man page for the "round" family here or with man round in the terminal.

Edit, I'm not sure if I was clear enough; roundf and round both do the exact same thing, round a variable, the difference however, is that roundf returns a float, whereas round returns a double. A double is just a "float" of 8 bytes instead of 4, therefore a double is even more precise than a float. Ultimately it doesn't matter which you decide to use, since 4 more bytes is hardly anything.

Good luck!

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  • Thanks for your help, I was not sure what was going to happen if I used the construction float value = round( valueChangefloat *100.) Will it try to store a double in the float value output? After reading the man pages I used roundf and i worked.
    – Pål Ingsøy
    Oct 24 '16 at 22:56
  • Hmm, that's actually a great question. While I cannot find any answers online, i would assume however, that using round() on a float casts the return value back to a float before finally putting it inside the variable.
    – kluvin
    Oct 25 '16 at 6:01

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