CODEWITHSUNDEEP
ccastingcharhex
c_prog_90
c_prog_90

Reputation: 949

Hex to char conversion and dumping output

I am trying to assign the first 8bytes of a character buffer with "00 00 00 00 00 00 00 A0". I am able to verify the buffer is constructed right. Whenever i try to hexdump using my utility, i get unexpected output. Not sure, if i am missing something else here.

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

static void hexdump(const char *src, int count)
{
    int i;  

    if (count == 0)
        return;

    for (i = 0; i < count; ++i) {

        printf("%02x ", src[i]);
        if ((i + 1) % 16 == 0)
            printf("\n");
    }   
    printf("\n");
}

int main() {
   char msg_buff[148];
   memset(msg_buff, 0, 148);
   int a[8] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xA0};
   sprintf(msg_buff, "%02x %02X %02X %02X %02X %02X %02X %02X", a[0], a[1], 
 a[2], a[3], a[4], a[5], a[6], a[7], a[8]);
   printf("packet %s \n", msg_buff); // 00 00 00 00 00 00 00 A0
   hexdump(msg_buff, 148);
}

My output

packet 00 00 00 00 00 00 00 A0 
30 30 20 30 30 20 30 30 20 30 30 20 30 30 20 30 
30 20 30 30 20 41 30 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 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 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 00 00 00 00 00 00 00 00 00 00 00 00 00 
00 00 00 00

Expected output

packet 00 00 00 00 00 00 00 A0 
00 00 00 00 00 00 00 A0 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 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 
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 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

Upvotes: 0

Views: 119

Answers (2)

Gena
Gena

Reputation: 48

Firstly, you need to delete a[8] from the following function in your code, because the length of a[] is 8, however your code has 9 members:

sprintf(msg_buff, "%02X %02X %02X %02X %02X %02X %02X %02X", a[0], a[1], a[2], a[3], a[4], a[5], a[6], a[7], a[8]);

Secondly, you need to change your defined variables type, your code should look like the following:

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

static void hexdump(const char *src, int count)
{
    int i;

    if (count == 0)
        return;

    for (i = 0; i < count; ++i) {

        printf("%02x ", src[i]);
        if ((i + 1) % 16 == 0)
            printf("\n");
    }
    printf("\n");
}

int main() {

    unsigned char  msg_buff[148];
    memset(msg_buff, 0, 148);
    unsigned char  a[8] = { 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0xA0 };
    sprintf(msg_buff, "%02X %02X %02X %02X %02X %02X %02X %02X", a[0], a[1], a[2], a[3], a[4], a[5], a[6], a[7]);
    printf("packet %s \n", msg_buff); // 00 00 00 00 00 00 00 A0
    hexdump(msg_buff, 148);

    return 0;
}

Upvotes: 1

0___________
0___________

Reputation: 67638

Change hexdump(msg_buff, 148);

to hexdump(a, 8);

In your code you are dumping the string

Upvotes: 0

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