CareerCup

This is the correct way:
char* strcyp(char* dst, const char* src)
{
char* ret = dst;
while(*dst++=*src++);
return ret;
}

while(*src!='/0')
{

des=src;

src++;

}

Assuming des has allocated space just like strcpy

int n = 0;
while ( *src != '\0' )
{
   *des++ = *src++;
   n++;   
}
return n;

char *temp=src;

while((*dst++=*src++)!='\0');
return(src-temp-1);

I think, its a strcpy(), so you need to append a '\0' at the end, none of the programs listed above are doing that.

I think in C, No null-character is implicitly appended to the end of destination in strcpy, so destination will only be null-terminated if the length of the C string in source is less than num. You have to clarify this with the interviewer as to what he wants

I think the catch here is to check if the source and destination memory overlap or not, which requires calculating the len including '\0'. And possibly using memcpy to copy the amount of non overlapping mem size in loop until it copies completely.