怎麼把檔案以16進位制寫入檔案呢。比如，開啟Editplus,開啟一個exe檔案或者其他，會顯示如下：

4D 5A 90 00 03 00 00 00  04 00 00 00 FF FF 00 00
B8 00 00 00 00 00 00 00  40 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00  00 00 00 00 00 01 00 00
0E 1F BA 0E 00 B4 09 CD  21 B8 01 4C CD 21 54 68
69 73 20 70 72 6F 67 72  61 6D 20 63 61 6E 6E 6F
74 20 62 65 20 72 75 6E  20 69 6E 20 44 4F 53 20
6D 6F 64 65 2E 0D 0D 0A  24 00 00 00 00 00 00 00
51 13 E2 96 15 72 8C C5  15 72 8C C5 15 72 8C C5
1C 0A 1F C5 1D 72 8C C5  86 3C 14 C5 14 72 8C C5
7A 04 12 C5 14 72 8C C5  7A 04 26 C5 07 72 8C C5
7A 04 10 C5 10 72 8C C5  15 72 8D C5 1B 73 8C C5
7A 04 27 C5 05 72 8C C5  7A 04 16 C5 14 72 8C C5
 

我們有時候寫東西，很希望存入檔案的也是這樣的東西，這樣就涉及到怎麼把字元或其他int型別轉換成16進位制。

#include <stdio.h>
#include <string.h>

int main(int argc,char *argv[])
{
	char *strTest = "I am OK!don't worry.";
	int strLen=strlen(strTest);
	int i=0;
	FILE *fp;
	if((fp=fopen("C:\\text.txt","wb")) == NULL)
	{
		printf("file open failed!");
		return 0;
	}
	printf("%d\n",strLen);
	while(i<strLen)
	{
	fprintf(fp,"%02x",strTest[i++]);
	}
	return 1;
}