C++失败题
class BYTE main(){ BYTE * pByte = new BYTE[4]; for(int i = 0; i < 4; i++) { *pByte = i; pByte++； } }
内存错误，未初始化？
实现字符串拷贝函数strcpy()
#include <iostream> using namespace std;
char* strcpy(char* dest, const char *src ) { // char* pdest = static_cast<char*>(dest); // const char* psrc = static_cast<const char*>(src); if((dest==NULL)||(src==NULL)) throw"error"; char* strdest = dest; while((*dest++ = *src++)!='\0'); return strdest; }
int main() { char* sdest = (char*)malloc(strlen(str)); char str[] = "0123456789"; strcpy( sdest, str); cout<< sdest<<endl; return 0; free(sdest); }
实现内存拷贝函数memcpy()
#include <iostream>
using namespace std;
void* memcpy(void * dest, const void *src, size_t count ) { char* pdest = static_cast<char*>(dest); const char* psrc = static_cast<char*>(src); if(pdest>psrc && pdest<psrc+count) { for(size_t i=count-1; i!=1; --i) pdest[i] = psrc[i]; } else { for(size_t i=0; i<count; ++i) pdest[i]=psrc[i]; } return dest; } int main() { char src[]= "0123456789"; memcpy( str+1; str+0; 9); cout<< str<<endl; return 0; }
二、编写一函数实现子字符串查找 char *strstr(char* str, char * substr)
main() { char b[]="0123456789ABCDEF"; int c[64],d,i=0,base=16; long n; scanf("%ld",&n); do{ c[i]= ;i++;n=n/base; }while(n!=0); for(--i;i>=0;--i) {d=c[i];printf("%c",b[d]);} getch(); } int AnsiString::Pos(const AnsiString& subStr) { int len=subStr.Length(); int p=0; for(int i=0;i<DataLen;i++) { if(i+1+len<=DataLen) { if(SubString(i+1,len)==subStr) { p=i+1; break; } } else { break; } } return p; }
AnsiString AnsiString::SubString(int index, int count) { index--; if(index+count>DataLen) { count=DataLen-index; } char* tmp=new char[count+1]; memcpy(tmp,Data+index,count); tmp[count]=0; AnsiString Result=tmp; delete []tmp; return Result; } XOR eax,eax(156252207) 22:00:39 pos函数就是 struct A { B*pB; } struct B { A* pA; }
一、实现编译通过：
预声明
struct B; struct A { B * pB; }; struct B { A* pA; };