Why do we need to memset always with zero?

Question

Whenever we use `memset` we set it with zero. Why? Why not with 1 or 2 or something else. Also, setting a struct to 0 seems to work but setting to 1 doesn't: ``` typedef struct abc{ int a; } abc; int main() { abc* ab; memset(ab, 0, sizeof(abc));// it sets abc->a = 0; correct } ``` But instead of `0` if I use `1` like: ``` memset(ab, 1, sizeof(abc)); ``` then the value of `abc->a = garbage` or `not equals to 1` Why?

Accepted Answer

You don't always need to `memset` to 0, this is just the most common (and useful) thing to do.

`memset` sets each byte to some given value. An `int` consists of 4 bytes, so, when `memset`ing to `1`, you'd set each of those 4 to `1`, then you'd have `00000001 | 00000001 | 00000001 | 00000001`2 = `16843009`10 (the first numbers are in binary, the last in decimal).

Also - note that you're never allocating memory for `ab`. Even though your code may work now, it's not safe. This would be:

```
abc ab;
memset(&ab, 0, sizeof(abc));
```

Why do we need to memset always with zero?

Solution

Problem