CODEWITHSUNDEEP
cwinapi
Santhosh Pai
Santhosh Pai

Reputation: 2635

conversion from BYTE to DWORD

I have written a code to convert ip to decimal and it seems to give an unexpected results , this is because of conversion mismatch from BYTE to DWORD .

Is there a way to convert byte variable to word , the typecast doesn't seem to work .

Here is the portion of the code 

  //function to convert ip 2 decimal 
   DWORD ip2dec(DWORD a ,DWORD b,DWORD c,DWORD d)
   {  

     DWORD dec;
     a=a*16777216;
     b=b*65536;
     c=c*256;
     dec=a+b+c+d;

     return dec;

  }

int main()
{
   BYTE a,b,c,d;
   /* some operations to split the octets and store them in a,b,c,d */
   DWORD res=ip2dec(a,b,c,d);
   printf("The converted decimal value = %d",dec);
}

I'm getting the value as -1062731519 instead of 3232235777 .

Upvotes: 0

Views: 3342

Answers (5)

Elangovan Sundar Rajan
Elangovan Sundar Rajan

Reputation: 1

#include  <stdio.h>

int main(void)
{

    short a[] = {0x11,0x22,0x33,0x44};
    int b = 0;

     b = (a[0] << 24 ) | ( a[1] << 16 ) | (a[2] << 8 ) | ( a[3] );

    printf("Size of short  %d \nSize of int  %d ", sizeof(short), sizeof(int));

    printf("\n\nValue of B is %x", b);
    return 0;
}

Upvotes: 0

sundq
sundq

Reputation: 763

You can do like this:

DWORD dec = 0;
BYTE *pdec = (BYTE *)&dec;
pdec[0] = a;
pdec[1] = b;
pdec[2] = c;
pdec[3] = d;

Upvotes: 2

Manas
Manas

Reputation: 608

Try the MAKEWORD() macro. But using %d in printf will still give you a wrong output.

Upvotes: 2

Curt
Curt

Reputation: 5722

Your conversion is probably right, but your printf statement is not.

Use "%u" instead of "%d".

Upvotes: 3

NPE
NPE

Reputation: 500893

Even though DWORD is unsigned, you are printing it out as if it were signed (%d). Try %u instead.

Upvotes: 3

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