Implement and test a memcpy function

The function copies memory block pointed by src into memory block pointed by dst. 1. Request the types of arguments and return value (thus determing the real declaration: void memcpy( void* src, void* dst, size_t size ); 2. Request the units of size. 3. Mention the case of overlapping src and dst blocks. Be very careful about this case. void memcpy( void* src, void* dst, size_t size ) { char *pc_src = src, *pc_dst = dst; //in C++ this will require an explicit cast if(pc_dst <= p_src ) for( char* it_src = pc_src, *it_dst = pc_dst; it_src < pc_src + size_t; it_src++, it_dst++ ) *it_dst = *it_src; else for( char* it_src = pc_src + size-1, *it_dst = pc_dst + size-1; it_src >= pc_src; it_src--, it_dst-- ) *it_dst = *it_src; } Now I'm too lazy to write the tests, but do mention the cases: 1. A usual case. Also check that the memory around src and dst doesn't change. 2. A case of overlapping blocks: src before and beyond dst. Also src and dst at the same address. 3. size = 1 and size = 0 cases. 4. You may be asked to write a case when memory is copied between different data types (e.g. unsidned int and char[4])

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elegant solution
By jagatsastry on Thursday, August 30, 2007 (UMST)

void* memcpy(void* src, const void* dest, size_t size) { char*a=(char*)src; char*b=(char*)dest; if(a<b) { if(a>b+size) exit(OVERLAP); for(int i=0;i<size;i++) *(b+i)=*(a+i); } else { if(b>a+size) exit(OVERLAP); it i; for(int i=0;i<size;i++) *(b+i)=*(a+i); } }
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Does not take care ofoverlap
By mjeewani on Saturday, September 27, 2008 (UMST)

Memcpy does not take care of overlap, If the buffer overlaps you should use memmove.
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