将两个字符转换为一个字节

/************************************************************ 将两个字符转换为一个字节，由于基本类型范围的影响， 其中包含了一种巧合即当_2asc_to_1b这个函数在转换例子中的"e1"时， 能够转换成功，因为e0转换完是2e0,由于超出了unsigned char的范围， 2将被丢弃，正好是e0. *************************************************************/ #include <stdio.h> unsigned char _2asc_to_1b(unsigned char* buff) { unsigned char b2,b1; b2 = *(buff); if(b2<=0x39) b1=(b2-0x30)<<4; else b1=(b2-0x41+10)<<4; b2 = *(buff+1); if(b2<=0x39) b1+=(b2-0x30); else b1+=(b2-0x41+10); return b1; } unsigned char my_2asc_to_1b(unsigned char* buff) { unsigned char b2,b1; b2 = *(buff); if(b2<=0x39) b1=(b2-0x30)<<4; else b1=(b2-0x61+10)<<4; b2 = *(buff+1); if(b2<=0x39) b1+=(b2-0x30); else b1+=(b2-0x61+10); return b1; } int main(int argc, char *argv[]) { char *str = "10e1"; char *str1 = "ed6a"; unsigned char tar1[4] = {0}; unsigned char tar2[4] = {0}; printf("str:%s str1:%s\n",str,str1); tar1[0] = _2asc_to_1b(str); tar1[1] = _2asc_to_1b(str+2); tar1[2] = _2asc_to_1b(str1); tar1[3] = _2asc_to_1b(str1+2); printf("_2asc:%02x%02x %02x%02x\n",tar1[0],tar1[1],tar1[2],tar1[3]); tar2[0] = my_2asc_to_1b(str); tar2[1] = my_2asc_to_1b(str+2); tar2[2] = my_2asc_to_1b(str1); tar2[3] = my_2asc_to_1b(str1+2); printf("my_sc:%02x%02x %02x%02x\n",tar2[0],tar2[1],tar2[2],tar2[3]); }