学步园

一、代码

1.1 头文件

////////////////////////////////////////////////////////////////
//
//Descript: base64 encode and decode.
//  Author: guowenyan
//    Date: 2013.12.09
//
////////////////////////////////////////////////////////////////
#pragma once
#include <string>

class base64
{
public:
	bool Encode(const char* data, unsigned int len, std::string& str_result);
	bool Decode(const char* data, unsigned int len, std::string& str_result);
};

1.2 实现文件

////////////////////////////////////////////////////////////////
//
//Descript: base64 encode and decode.
//  Author: guowenyan
//    Date: 2013.12.09
//
////////////////////////////////////////////////////////////////
#include "base64.h"

using namespace std;


bool base64::encode(const char* data, unsigned int len, string& str_result)
{
	if ( NULL == data || len <= 0)
	{
		return false;
	}

	char encode_table[65] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";

	char a, b, c;
	int line_len = 0;
	for ( int i=0; i<len/3; ++i )
	{
		a = *data++;
		b = *data++;
		c = *data++;

		str_result += encode_table[a >> 2];
		str_result += encode_table[((a << 4) | (b >> 4)) & 0x3F];
		str_result += encode_table[((b << 2) | (c >> 6)) & 0x3F];
		str_result += encode_table[c & 0x3F];

		if (line_len += 4, 76 == line_len)
		{
			str_result += "\r\n";
			line_len = 0;
		}
	}

	int mod = len % 3;
	if ( 1 == mod )
	{
		a = *data++;

		str_result += encode_table[(a & 0xFC) >> 2];
		str_result += encode_table[(a & 0x03) << 4];
		str_result += "==";
	}
	else if ( 2 == mod )
	{
		a = *data++;
		b = *data++;

		str_result += encode_table[(a & 0xFC) >> 2];
		str_result += encode_table[((a & 0x03) << 4) | ((b & 0xF0) >> 4)];
		str_result += encode_table[(b & 0x0F) << 2];;
		str_result += "=";
	}

	return true;
}

bool base64::decode(const char* data, unsigned int len, string& str_result)
{
	if ( NULL == data || len <= 0)
	{
		return false;
	}

	const char decode_table[] =
	{
		-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
		-1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,
		62, // '+'
		-1, -1, -1,
		63, // '/'
		52, 53, 54, 55, 56, 57, 58, 59, 60, 61, // '0'-'9'
		-1, -1, -1, -1, -1, -1, -1,
		0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12,
		13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, // 'A'-'Z'
		-1, -1, -1, -1, -1, -1,
		26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38,
		39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, // 'a'-'z'
	};

	char a, b, c, d;
	int i=0;
	while ( i < len )
	{
		if ( '\r' == *data || '\n' == *data )
		{
			data++;
			i++;
			continue;
		}

		a = decode_table[*data++];
		b = decode_table[*data++];
		c = decode_table[*data++];
		d = decode_table[*data++];
		str_result += ( (a << 2) | ((b >> 4) & 0x03) );
		if ( -1 != c )  str_result += ( (b << 4) | ((c >> 2) & 0x0F) );
		if ( -1 != d )  str_result += ( (c << 6) | (d & 0x3F) );

		i += 4;
	}

	return true;
}

1.3 主函数

#include <iostream>
using namespace std;

#include "base64.h"

int main()
{
	//
	//char ssz[] = "abcdef1234567 abcdef1234567 abcdef1234567 abcdef1234567 abcdef1234567 abcdef1234567";
	char sz[] = "123456adbde";
	unsigned int in_len = strlen(sz);
	cout<<"sz:"<<sz<<","<<in_len<<endl;


	base64 test;

	//encode
	string str_encode;
	test.Encode(sz, in_len, str_encode);
	cout<<"str_encode:"<<str_encode.c_str()<<","<<str_encode.length()<<endl;

	//decode
	string str_decode;
	test.Decode(str_encode.c_str(), str_encode.length(), str_decode);
	cout<<"str_decode:"<<str_decode.c_str()<<","<<str_decode.length()<<endl;

	return 0;
}

二、结果