Base64编解码程序 附带源码 可以把文件编码为bmp图片

#include "StdAfx.h" #include "Base64.h" //以下函数检查str为NULL时的情况,cnt表示str中的字节个数 size_t Base64Encode(const unsigned char* str, size_t cnt, char* strout) //当strout为NULL时,返回所需的字节数,计算公式是((cnt-1)/3+1)*4 //否则编码写入strout中,并返回((cnt-1)/3+1)*4 { size_t i,j,k; size_t off,num; const static char strbase[]="ABCDEFGHIJKLMNOPQRSTUVWXYZ" "abcdefghijklmnopqrstuvwxyz" "0123456789+/"; if(0==str || 0==cnt) return 0; if(0==strout) return ((cnt-1)/3+1)<<2; off=cnt%3; num=cnt/3; for(i=0;i<num;++i) { j=i<<2;//i*4 k=i*3; strout[j] =strbase[str[k]>>2]; strout[j+1]=strbase[((str[k]<<4)|(str[k+1]>>4))&0x3F]; strout[j+2]=strbase[((str[k+1]<<2)|(str[k+2]>>6))&0x3F]; strout[j+3]=strbase[str[k+2]&0x3F]; } if(1==off) { j=i<<2;//i*4 k=i*3; strout[j] =strbase[str[k]>>2]; strout[j+1]=strbase[(str[k]<<4)&0x3F]; strout[j+2]='='; strout[j+3]='='; return ((cnt-1)/3+1)<<2; } else if(2==off) { j=i<<2;//i*4 k=i*3; strout[j] =strbase[str[k]>>2]; strout[j+1]=strbase[((str[k]<<4)|(str[k+1]>>4))&0x3F]; strout[j+2]=strbase[(str[k+1]<<2)&0x3F]; strout[j+3]='='; return ((cnt-1)/3+1)<<2; } else return ((cnt-1)/3+1)<<2; } size_t Base64Decode(const unsigned char* str, size_t cnt, unsigned char* strout) //当strout为NULL时,返回所需的字节数,cnt须为4的倍数,若不是,则返回0 //若str不能解码,则也返回0,可以解码的情况下,返回写入strout的字节数 //字节数计算公式是:cnt/4*3-num('='),num('=')表示str结尾处的'='个数(只考虑0-2个) { size_t i,j,k; size_t off(cnt%4),num; const static unsigned char strbase[]= "[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[\x3e[[[\x3f\x34\x35"//'1' "\x36\x37\x38\x39\x3a\x3b\x3c\x3d[[[][[[\x00\x01\x02\x03\x04\x05\x06"//'G' "\x07\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19"//'Z' "[[[[[[\x1a\x1b\x1c\x1d\x1e\x1f\x20\x21\x22\x23\x24\x25\x26\x27\x28\x29\x2a"//'Q' "\x2b\x2c\x2d\x2e\x2f\x30\x31\x32\x33[[[[["//前128个字符结束了 "[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[" "[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[" "[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[" "[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[[";//'['表示其余值;']'表示'=' if(0==str || 0==cnt || 0!=off) return 0; if(0==strout) { if('='==str[cnt-1]) { if('='==str[cnt-2]) return (cnt>>2)*3-2; else return (cnt>>2)*3-1; } else return (cnt>>2)*3; } for(i=0,num=cnt/4-1;i<num;++i) { j=i*3; k=i<<2;//i*4 if('['==strbase[str[k]] || ']'==strbase[str[k]] || '['==strbase[str[k+1]] || ']'==strbase[str[k+1]] || '['==strbase[str[k+2]] || '['==strbase[str[k+3]]) return 0; strout[j] =(strbase[str[k]]<<2)|(strbase[str[k+1]]>>4); strout[j+1]=(strbase[str[k+1]]<<4)|(strbase[str[k+2]]>>2); strout[j+2]=(strbase[str[k+2]]<<6)|strbase[str[k+3]]; } j=i*3; k=i<<2;//i*4 if('['==strbase[str[k]] || ']'==strbase[str[k]] || '['==strbase[str[k+1]] || ']'==strbase[str[k+1]] || '['==strbase[str[k+2]] || '['==strbase[str[k+3]]) return 0; strout[j] =(strbase[str[k]]<<2)|(strbase[str[k+1]]>>4); if(']'==strbase[str[k+2]]) { if(']'!=strbase[str[k+3]]) return 0; else return (cnt>>2)*3-2; } else { strout[j+1]=(strbase[str[k+1]]<<4)|(strbase[str[k+2]]>>2); if(']'!=strbase[str[k+3]]) { strout[j+2]=(strbase[str[k+2]]<<6)|strbase[str[k+3]]; return (cnt>>2)*3; } else return (cnt>>2)*3-1; } } //////////////////////////////////// HadPtr::HadPtr(void* p):m_ptr(p) { } HadPtr::~HadPtr() { if(m_ptr) { free(m_ptr); m_ptr=0; } } void HadPtr::Attach(void* p) { if(m_ptr) free(m_ptr); m_ptr=p; } void* HadPtr::GetPtr() { return m_ptr; } const void* HadPtr::GetPtr()const { return m_ptr; } void* HadPtr::Detach() { void* pret=m_ptr; m_ptr=0; return pret; }