CODEWITHSUNDEEP
c++carraysinitialization
eugene
eugene

Reputation: 41665

Array initialization with {0}, {0,}?

Say I want to initialize myArray 

char myArray[MAX] = {0};  
char myArray[MAX] = {0,};  
char myArray[MAX]; memset(myArray, 0, MAX);

Are they all equal or any preferred over another?

Thank you

Upvotes: 43

Views: 45606

Answers (6)

user541686
user541686

Reputation: 210352

Actually, in C++, I personally recommend:

char myArray[MAX] = {};

They all do the same thing, but I like this one better in C++; it's the most succinct. (Unfortunately this isn't valid in C.)

By the way, do note that char myArray[MAX] = {1}; does not initialize all values to 1! It only initializes the first value to 1, and the rest to zero. Because of this, I recommend you don't write char myArray[MAX] = {0}; as it's a little bit misleading for some people, even though it works correctly.

Upvotes: 49

Bogdan Ruzhitskiy
Bogdan Ruzhitskiy

Reputation: 1237

You can use also bzero fn (write zero-valued bytes)

#include <strings.h>
void bzero(void *s, size_t n)

http://linux.die.net/man/3/bzero

Upvotes: 0

Sylvain Defresne
Sylvain Defresne

Reputation: 44473

They are equivalent regarding the generated code (at least in optimised builds) because when an array is initialised with {0} syntax, all values that are not explicitly specified are implicitly initialised with 0, and the compiler will know enough to insert a call to memset.

The only difference is thus stylistic. The choice will depend on the coding standard you use, or your personal preferences.

Upvotes: 27

iammilind
iammilind

Reputation: 69978

Assuming that you always want to initialize with 0.

--> Your first way and 2nd way are same. I prefer 1st.

--> Third way of memset() should be used when you want to assign 0s other than initialization.

--> If this array is expected to initialized only once, then you can put static keyword ahead of it, so that compiler will do the job for you (no runtime overhead)

Upvotes: 1

Jhaliya - Praveen Sharma
Jhaliya - Praveen Sharma

Reputation: 31722

Either can be used

But I feel the below more understandable and readable .. 

  char myArray[MAX]; 
  memset(myArray, 0, MAX);

Upvotes: 1

Sarfaraz Nawaz
Sarfaraz Nawaz

Reputation: 361302

I think the first solution is best.

char myArray[MAX] = {0};  //best of all

Upvotes: 6

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