Should C++ programmer avoid memset?

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遇见更好的自我
遇见更好的自我 2020-12-02 20:17

I heard a saying that c++ programmers should avoid memset,

class ArrInit {
    //! int a[1024] = { 0 };
    int a[1024];
public:
    ArrInit() {  memset(a, 0         


        
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  •  旧巷少年郎
    2020-12-02 20:50

    What's wrong with memset in C++ is mostly the same thing that's wrong with memset in C. memset fills memory region with physical zero-bit pattern, while in reality in virtually 100% of cases you need to fill an array with logical zero-values of corresponding type. In C language, memset is only guaranteed to properly initialize memory for integer types (and its validity for all integer types, as opposed to just char types, is a relatively recent guarantee added to C language specification). It is not guaranteed to properly set to zero any floating point values, it is not guaranteed to produce proper null-pointers.

    Of course, the above might be seen as excessively pedantic, since the additional standards and conventions active on the given platform might (and most certainly will) extend the applicability of memset, but I would still suggest following the Occam's razor principle here: don't rely on any other standards and conventions unless you really really have to. C++ language (as well a C) offers several language-level features that let you safely initialize your aggregate objects with proper zero values of proper type. Other answers already mentioned these features.

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