CODEWITHSUNDEEP
cmemset
Tom
Tom

Reputation: 13

initialize float-type array using memset

I have a pointer float *ptr, after dynamic allocation with length n, I want to initialize this array with zero or one, so I use memset(ptr,0,n*sizeof(float)) or memset(ptr,1,n*sizeof(float)). Is this legal? Because the second argument of memset is int-type, I'm afraid it cannot be applied to float-type.

Upvotes: 1

Views: 4136

Answers (2)

chux
chux

Reputation: 153303

memset(ptr,1,n*sizeof(float)). Is this legal?

No, not to set the value of the float to 1.0f as the encoding of a float in not the bytes 1,1,1,1 @James Picone

memset(ptr,0,n*sizeof(float)) or better memset(ptr, 0, sizeof *ptr * n) will set every byte to 0. This is certainly the encoding for a float 0.0f.

To set every element of a float array to 1.0f or any value, simply use a loop.

float initial_value = 1.0f;
for (size_t i = 0; i < n; i++) {
   ptr[i] = initial_value;
}

Upvotes: 3

John Zwinck
John Zwinck

Reputation: 249093

Initializing floats to all-bytes-zero is OK (it will produce float 0.0). But all-bytes-1 is not reasonable, because it will produce a "garbage" value (but the same value every time).

Upvotes: 2

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