How to initialize array to 0 in C?

c arrays initialization
Claudiu picture Claudiu · Apr 7, 2010 · Viewed 302.3k times · Source

I need a big null array in C as a global. Is there any way to do this besides typing out

char ZEROARRAY[1024] = {0, 0, 0, /* ... 1021 more times... */ };

?

Answer

John Kugelman picture John Kugelman · Apr 7, 2010

Global variables and static variables are automatically initialized to zero. If you have simply

char ZEROARRAY[1024];

at global scope it will be all zeros at runtime. But actually there is a shorthand syntax if you had a local array. If an array is partially initialized, elements that are not initialized receive the value 0 of the appropriate type. You could write:

char ZEROARRAY[1024] = {0};

The compiler would fill the unwritten entries with zeros. Alternatively you could use memset to initialize the array at program startup:

memset(ZEROARRAY, 0, 1024);

That would be useful if you had changed it and wanted to reset it back to all zeros.

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