字符串拷贝函数strcpy的几种实现思想方式

来源：互联网发布：js 定时器缺点编辑：程序博客网时间：2024/05/21 22:51

#include <iostream>  #include <assert.h>//strcpy标准实现char* CustomStrCpy1( char* Dest, const char* Src ){if( nullptr == Dest || nullptr == Src ){assert( false );return nullptr;}char* p = Dest;while( *p++=*Src++ );return Dest;}//strcpy内存实现char* CustomStrCpy2( char* Dest, const char* Src ){if( nullptr == Dest || nullptr == Src ){assert( false );return nullptr;}memcpy( Dest, Src, strlen( Src ) + 1 );return Dest;}//strcpy数组实现char* CustomStrCpy3( char* Dest, const char* Src ){if( nullptr == Dest || nullptr == Src ){assert( false );return nullptr;}const size_t SrcLen = strlen( Src );for( size_t i = 0; i <= SrcLen; ++i ){Dest[ i ] = Src[ i ];}return Dest;}//strcpy递归 char* CustomStrCpy4( char* Dest, const char* Src, int DestOffset = 0 ){if( nullptr == Dest || nullptr == Src ){assert( false );return nullptr;}*Dest = *Src;if( '\0' == *Src ){return Dest - DestOffset;}return CustomStrCpy4( Dest + 1, Src + 1, DestOffset + 1 );}int main()  {//测试char Test[ 32 ];std::cout<<CustomStrCpy1( Test, "123" )<<std::endl;std::cout<<CustomStrCpy2( Test, "456" )<<std::endl;std::cout<<CustomStrCpy3( Test, "789" )<<std::endl;std::cout<<CustomStrCpy4( Test, "123" )<<std::endl;//效率的话大家可以尝试自己修改代码比对一下//不过我觉得应该是内存思想方式效率最高//其他函数如strcat的实现也都差不多return 0;  }

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