额...这个程序不能防止拷贝超出界限...

#include <iostream>
using std::cout;
using std::endl;
char *strcpy(char* strDest ,const char* strSrc);
int main ()
{
    char adress[ ]="String Copy";
    char Dst [ ]="Why fdfefdsfefsdf";
    cout<<strcpy(Dst,adress)<<endl;
    system ("Pause");
    return 0;
}
char *strcpy(char* strDest ,const char* strSrc)
{
    if ( *strDest == NULL || *strSrc == NULL )
    {  
        cout<<"strDest == NULL || strSrc == NULL"<<endl;  
    }
    while ( (*strDest++ = *strSrc++ ) != '\0' )  
    {
         ;
    }
    return strDest;
}

主要原因是目标字符串的长度没有源字符串的长.....

#include<iostream.h>
#include <malloc.h>
char *strcpy(char* strDest ,const char* strSrc);
void main ()
{
    char adress[]="String Copy woieuoifji";
    char *Dst = 0;
    Dst = strcpy(Dst,adress);
    cout<<Dst<<endl;   
}
char *strcpy(char* strDest ,const char* strSrc)
{
    int i = 0;
    if ( strSrc == NULL )
    {   
        cout<<"strDest == NULL || strSrc == NULL"<<endl;   
    }
   else
   {
       strDest = (char *) malloc (2*sizeof(char));
       *(strDest+1)='\0';
   }
    while ( *strSrc != '\0' )   
    {
        *(strDest+i) = *strSrc++;
        ++i;
        strDest = (char *) realloc (strDest, (i+1)*sizeof(char));
        *(strDest+i) = '\0';
    }
    return strDest;
}

你要确保你向拷贝函数传递的参数的生存期，也就是要把他放到堆中，不能让系统默认放在栈中 这样函数执行完了就会被释放掉

说的在理