CODEWITHSUNDEEP
chexbyteprintfendianness
nadavbara
nadavbara

Reputation: 23

how to print 2 or 4 bytes in hex format in C

I need to print bytes in hexadecimal form in C. All I’ve managed to do is to print 1 byte at a time, where my program has to support the option for 1, 2 or 4 bytes (size parameter). this is my function:

void memDisaply(char* filename, int size) {

char sentence [100];
unsigned int str[20];
int length,i;
unsigned char* ptr;

printf("Please enter <address> <length>\n");

fflush(stdin);
fgets(sentence,100,stdin);
fgets(sentence,100,stdin);

    sscanf (sentence,"%x %d",str,&length);
    ptr = (unsigned char*)str;

    for (i=0 ; i< length ; i++) {
        printf ("%02x",(unsigned int)ptr[i]);
    }

    /*reset values*/
    length = 0;
    i = 0;
    ptr = NULL;
}

the output is as follows (where size=1, and length= 10):

31 ED 5E 89 E1 83 E4 F0 50 54

I need that when size = 2 and length = 5 that the output will be:

ED31 895E 83E1 F0E4 5450

(notice the little endian) I somehow need to use the size argument to alter the output but I don't know how. I assume it got something to do with the %02x format, and I've tried %04x but all I got was:

0031 00ED 005E 0089 00E1 0083 00E4 00F0 0050 0054

Upvotes: 2

Views: 21543

Answers (1)

ouah
ouah

Reputation: 145849

Read two bytes by two bytes and do:

printf ("%04x", (unsigned int) ptr[i] | (unsigned int) ptr[i + 1] << 8);

Upvotes: 2

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