CODEWITHSUNDEEP
cfunctionparam
Maluvel
Maluvel

Reputation: 455

change function param value inside function in C

Stupid question, is it a good way to change value of function parameter inside the function or create another variable to hold it, which one is better? eg : 

s16 functionA(s16 sum) {
u8 addy = 5; 
sum += addy; 
return sum;
}

OR

s16 functionA(s16 origin) {
u8 addy = 5; 
s16 sum = origin + addy; 
return sum;
}

Thanks.

Upvotes: 1

Views: 121

Answers (3)

unwind
unwind

Reputation: 400069

It's fine to write to the parameter, and might even be better performance-wise depending on how clever the compiler is.

On the other hand, your example could also be written as:

s16 functionA(s16 sum)
{
  const u8 addy = 5; /* Assuming this is more complex in reality. */
  return sum + addy;
}

There's no point in assigning to sum and then returning it, the two statements can be combined.

Upvotes: 2

Benoit Blanchon
Benoit Blanchon

Reputation: 14571

Since the second one doesn't improve readability, I would choose the first one.

Moreover, it saves 2 bytes on the stack, which can be good in a embedded environment (but it's very likely that the compiler will optimize it).

Upvotes: 0

Paul Evans
Paul Evans

Reputation: 27577

OR

s16 functionA(s16 origin) {
    u8 addy = 5;
    return origin + addy;
}

Upvotes: 0

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