c语言16进制字符串转字节数组-白红宇

c语言16进制字符串转字节数组

阅读量：3945 次

发布时间：2019-05-24

本文共 2405 字，大约阅读时间需要 8 分钟。

今天看代码看到两种16进制字符串转字节数组的方法，现贴出来相当于做个笔记了。

第一种：

1 #include
   
      2 #include
    
       3   4 void hex_str_to_byte(char *hex_str, int length, unsigned char *result)  5 {
     6     char h, l;  7     for(int i = 0; i < length/2; i++)  8     {
     9         if(*hex_str < 58) 10         {
    11             h = *hex_str - 48; 12         } 13         else if(*hex_str < 71) 14         {
    15             h = *hex_str - 55; 16         } 17         else 18         {
    19             h = *hex_str - 87; 20         } 21         hex_str++; 22         if(*hex_str < 58) 23         {
    24             l = *hex_str - 48; 25         } 26         else if(*hex_str < 71) 27         {
    28             l = *hex_str - 55; 29         } 30         else 31         {
    32             l = *hex_str - 87; 33         } 34         hex_str++; 35         *result++ = h<<4|l; 36     } 37 } 38  39 int main() 40 {
    41     char *str = "AB32333435363738393a3b3c3d3e3f40"; 42     unsigned char temp[16] = {
   0}; 43     hex_str_to_byte(str, strlen("AB32333435363738393a3b3c3d3e3f40"), temp); 44     for (int i = 0; i < 16; i++) 45     {
    46         printf("%x ", temp[i]); 47     } 48     printf("\n"); 49     return 0; 50 }

第二种：

36 #include
   
     37 #include
    
      38 #include
     
       39 void hex_str_to_byte(char *in, int len, unsigned char *out) 40 {
    41     char *str = (char *)malloc(len); 42     memset(str, 0, len); 43     memcpy(str, in, len); 44     for (int i = 0; i < len; i+=2) 45     {
    46         //小写转大写 47         if(str[i] >= 'a' && str[i] <= 'f') str[i] = str[i] - 0x20; 48         if(str[i+1] >= 'a' && str[i] <= 'f') str[i+1] = str[i+1] - 0x20; 49         //处理第前4位 50         if(str[i] >= 'A' && str[i] <= 'F') 51             out[i/2] = (str[i]-'A'+10)<<4; 52         else 53             out[i/2] = (str[i] & ~0x30)<<4; 54         //处理后4位, 并组合起来 55         if(str[i+1] >= 'A' && str[i+1] <= 'F') 56             out[i/2] |= (str[i+1]-'A'+10); 57         else 58             out[i/2] |= (str[i+1] & ~0x30); 59     } 60     free(str); 61 } 62  63 int main() 64 {
    65     char *str = "AB32333435363738393a3b3c3d3e3f40"; 66     unsigned char temp[16] = {
   0}; 67     hex_str_to_byte(str, strlen("AB32333435363738393a3b3c3d3e3f40"), temp); 68     for (int i = 0; i < 16; i++) 69     {
    70         printf("%x ", temp[i]); 71     } 72     printf("\n"); 73     return 0; 74 }