常用字节转换（字符串转16进制，16进制转字符串）

Java版：

private static byte charToByte(char c) { return (byte) "0123456789ABCDEF".indexOf(c); } public static String bytesToHexString(byte[] src){ StringBuilder stringBuilder = new StringBuilder(""); if (src == null || src.length <= 0) { return null; } for (int i = 0; i < src.length; i++) { int v = src[i] & 0xFF; String hv = Integer.toHexString(v); if (hv.length() < 2) { stringBuilder.append(0); } stringBuilder.append(hv); } return stringBuilder.toString(); } public static byte[] hexStringToBytes(String hexString) { if (hexString == null || hexString.equals("")) { return null; } hexString = hexString.toUpperCase(); int length = hexString.length() / 2; char[] hexChars = hexString.toCharArray(); byte[] d = new byte[length]; for (int i = 0; i < length; i++) { int pos = i * 2; d[i] = (byte) (charToByte(hexChars[pos]) << 4 | charToByte(hexChars[pos + 1])); } return d; }

c语言版：

/** * hex格式char转二进制 */ unsigned char hex_of_char(char c) { unsigned char tmp = 0; if(c >= '0' && c <= '9') { tmp = (c - '0'); } else if(c >= 'A' && c <= 'F') { tmp = (c - 'A' + 10); } else if(c >= 'a' && c <= 'f') { tmp = (c - 'a' + 10); } return tmp; } static char g_hex_map_table[] = "0123456789ABCDEF"; /** * 字节数组转hex格式字符串 * @param print_buf: 十六进制字符串buffer * @param print_buf_len: 十六进制字符串buffer长度 * @param bytes: 二进制数据 * @param bytes_len: 二进制数据长度 */ char* bytes_to_hex_string( char* print_buf, int print_buf_len, const unsigned char* bytes, int len) { int i = 0; /** * 入参校验 */ if(print_buf == NULL || bytes == NULL || (len * 2 + 1) > print_buf_len) { return NULL; } for(i = 0; i < len; i++) { print_buf[i * 2] = g_hex_map_table[(bytes[i] >> 4) & 0x0F]; print_buf[i * 2 + 1] = g_hex_map_table[(bytes[i]) & 0x0F]; } /** * 填充字符串结束符 */ print_buf[i * 2] = '\0'; /** * 返回目标地址 */ return print_buf; } /** * hex格式字符串转字节数组 * @param hex_string: 十六进制字符串 * @param hex_string_len: 十六进制字符串长度 * @param bytes: 二进制数据存储空间 * @param bytes_len: 目标空间长度 */ int hex_string_to_bytes( char* hex_string, int hex_string_len, unsigned char* bytes, int bytes_len) { int i = 0; /** * 校验十六进制字符串长度必须偶数，并且目标存储空间必须足够存放转换后的二进制数据 */ if((hex_string_len % 2 != 0) || (bytes_len * 2 < hex_string_len)) { return -1; } for(i = 0; i < hex_string_len; i += 2) { bytes[i/2] = ((hex_of_char(hex_string[i]) << 4) & 0xF0) | (hex_of_char(hex_string[i + 1]) & 0x0F); } return 1; }