C++如何进行Base64编码和解码_C++数据编码与传输格式实现

#include <string>
#include <vector>
<p>static const std::string base64_chars =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";</p><p>std::string base64_encode(const unsigned char* data, size_t len) {
std::string encoded;
int i = 0;
int j = 0;
unsigned char char_array_3[3];
unsigned char char_array_4[4];</p><pre class='brush:php;toolbar:false;'>while (len--) {
    char_array_3[i++] = *(data++);
    if (i == 3) {
        char_array_4[0] = (char_array_3[0] >> 2);
        char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + (char_array_3[1] >> 4);
        char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + (char_array_3[2] >> 6);
        char_array_4[3] = (char_array_3[2] & 0x3f);

        for (i = 0; i < 4; i++)
            encoded += base64_chars[char_array_4[i]];
        i = 0;
    }
}

if (i) {
    for (j = i; j < 3; j++)
        char_array_3[j] = '\0';

    char_array_4[0] = (char_array_3[0] >> 2);
    char_array_4[1] = ((char_array_3[0] & 0x03) << 4) + (char_array_3[1] >> 4);
    char_array_4[2] = ((char_array_3[1] & 0x0f) << 2) + (char_array_3[2] >> 6);
    char_array_4[3] = (char_array_3[2] & 0x3f);

    for (j = 0; j < i + 1; j++)
        encoded += base64_chars[char_array_4[j]];

    while (i++ < 3)
        encoded += '=';
}

return encoded;

std::vector<unsigned char> base64_decode(const std::string& encoded) {
    std::vector<unsigned char> decoded;
    int i = 0;
    int j = 0;
    unsigned char char_array_4[4], char_array_3[3];
<pre class='brush:php;toolbar:false;'>auto base64_index = [](char c) -> int {
    if (c >= 'A' && c <= 'Z') return c - 'A';
    if (c >= 'a' && c <= 'z') return c - 'a' + 26;
    if (c >= '0' && c <= '9') return c - '0' + 52;
    if (c == '+') return 62;
    if (c == '/') return 63;
    return -1;
};

for (char c : encoded) {
    if (c == '=') break;
    int value = base64_index(c);
    if (value == -1) continue;

    char_array_4[i++] = value;
    if (i == 4) {
        char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
        char_array_3[1] = ((char_array_4[1] & 0x0f) << 4) + ((char_array_4[2] & 0x3c) >> 2);
        char_array_3[2] = ((char_array_4[2] & 0x03) << 6) + char_array_4[3];

        for (j = 0; j < 3; j++)
            decoded.push_back(char_array_3[j]);
        i = 0;
    }
}

if (i > 0) {
    char_array_3[0] = (char_array_4[0] << 2) + ((char_array_4[1] & 0x30) >> 4);
    decoded.push_back(char_array_3[0]);

    if (i > 1) {
        char_array_3[1] = ((char_array_4[1] & 0x0f) << 4) + ((char_array_4[2] & 0x3c) >> 2);
        decoded.push_back(char_array_3[1]);
    }
}

return decoded;

#include <iostream>
<p>int main() {
std::string text = "Hello, Base64 in C++!";
std::string encoded = base64_encode((const unsigned char*)text.c_str(), text.length());
std::vector<unsigned char> decoded = base64_decode(encoded);</p><pre class='brush:php;toolbar:false;'>std::string result(decoded.begin(), decoded.end());

std::cout << "Original: " << text << std::endl;
std::cout << "Encoded:  " << encoded << std::endl;
std::cout << "Decoded:  " << result << std::endl;

return 0;

Original: Hello, Base64 in C++!
Encoded:  SGVsbG8sIEJhc2U2NCBpbiBDKysh
Decoded:  Hello, Base64 in C++!