c++ string 与 char 互转 以及base64

c++ string 与 char 互转

很简单如下

    char bts[] = {'A','B','C','D','E'};
    printf("%s\n",bts);
    //char to string
    std::string strBts = bts;
    std::cout << strBts << std::endl;

    //string to char
    char *theBts = (char *)strBts.c_str();
    printf("%s\n",theBts);

c++ base64 工具

//
//  base64.h
//  CPPWork
//  from http://stackoverflow.com/questions/180947/base64-decode-snippet-in-c
//  Created by cocoa on 16/8/5.
//  Copyright © 2016年 cc. All rights reserved.
//

#ifndef base64_h
#define base64_h

#include <string>

std::string base64_encode(unsigned char const* bytes_to_encode, unsigned int in_len);
std::string base64_decode(std::string const& encoded_string);

#endif /* base64_h */

//
//  base64.cpp
//  CPPWork
//
//  Created by cocoa on 16/8/5.
//  Copyright © 2016年 cc. All rights reserved.
//

#include "base64.h"
#include <iostream>

static const std::string base64_chars =
"ABCDEFGHIJKLMNOPQRSTUVWXYZ"
"abcdefghijklmnopqrstuvwxyz"
"0123456789+/";

static inline bool is_base64(unsigned char c) {
    return (isalnum(c) || (c == '+') || (c == '/'));
}

std::string base64_encode(unsigned char const* bytes_to_encode, unsigned int in_len) {
    std::string ret;
    int i = ;
    int j = ;
    unsigned char char_array_3[];
    unsigned char char_array_4[];

    while (in_len--) {
        char_array_3[i++] = *(bytes_to_encode++);
        if (i == ) {
            char_array_4[] = (char_array_3[] & 0xfc) >> ;
            char_array_4[] = ((char_array_3[] & 0x03) << ) + ((char_array_3[] & 0xf0) >> );
            char_array_4[] = ((char_array_3[] & 0x0f) << ) + ((char_array_3[] & 0xc0) >> );
            char_array_4[] = char_array_3[] & 0x3f;

            for(i = ; (i <) ; i++)
                ret += base64_chars[char_array_4[i]];
            i = ;
        }
    }

    if (i)
    {
        for(j = i; j < ; j++)
            char_array_3[j] = '\0';

        char_array_4[] = (char_array_3[] & 0xfc) >> ;
        char_array_4[] = ((char_array_3[] & 0x03) << ) + ((char_array_3[] & 0xf0) >> );
        char_array_4[] = ((char_array_3[] & 0x0f) << ) + ((char_array_3[] & 0xc0) >> );
        char_array_4[] = char_array_3[] & 0x3f;

        for (j = ; (j < i + ); j++)
            ret += base64_chars[char_array_4[j]];

        while((i++ < ))
            ret += '=';

    }

    return ret;

}
std::string base64_decode(std::string const& encoded_string) {
    int in_len = encoded_string.size();
    int i = ;
    int j = ;
    int in_ = ;
    unsigned char char_array_4[], char_array_3[];
    std::string ret;

    while (in_len-- && ( encoded_string[in_] != '=') && is_base64(encoded_string[in_])) {
        char_array_4[i++] = encoded_string[in_]; in_++;
        if (i ==) {
            for (i = ; i <; i++)
                char_array_4[i] = base64_chars.find(char_array_4[i]);

            char_array_3[] = (char_array_4[] << ) + ((char_array_4[] & 0x30) >> );
            char_array_3[] = ((char_array_4[] & 0xf) << ) + ((char_array_4[] & 0x3c) >> );
            char_array_3[] = ((char_array_4[] & 0x3) << ) + char_array_4[];

            for (i = ; (i < ); i++)
                ret += char_array_3[i];
            i = ;
        }
    }

    if (i) {
        for (j = i; j <; j++)
            char_array_4[j] = ;

        for (j = ; j <; j++)
            char_array_4[j] = base64_chars.find(char_array_4[j]);

        char_array_3[] = (char_array_4[] << ) + ((char_array_4[] & 0x30) >> );
        char_array_3[] = ((char_array_4[] & 0xf) << ) + ((char_array_4[] & 0x3c) >> );
        char_array_3[] = ((char_array_4[] & 0x3) << ) + char_array_4[];

        for (j = ; (j < i - ); j++) ret += char_array_3[j];
    }

    return ret;
}