Quick Conversion Question

**DougC** · 01-10-2003

Hi:

I have this function, converting the ASCII value in to a corresponding HEX and then doing a bitshift by 4. It does octal.

iReturnValue = (iReturnValue <<= 4) | ( (cmd[I] % '0') - 7 * (cmd[I] / 'A') );

if I want to change this to convert from to an integer from hexascii what needs to be changed?

iReturnValue = (iReturnValue >>= 4) | ( (cmd[I] % '0') - 7 * (cmd[I] / 'A') );

I thought this above, but it does not seem to work.
-------------------
The whole thing looks like this:

Code:

/*
char* cmd = 
"\002\006\105\060\060\060\060\060\060\060\060\061\106\003"; //Declaration of the buffer
	printf("Integer Value = %d\n", getValue(cmd));	//Retrieving the integer value from the last 4 bytes


int getValue(char* cmd)
{
	int iReturnValue = 0;					//Declaration and initialization of the returnValue variable.

	//Loop to iterate through the last 4 values in the array
	for(int I = g_ciBufferPrefixLength - 1; I < g_ciBufferLength - 1; I++)	
//Loop to iterate
	{
		//Converting the ASCII value in to a corresponding HEX and then doing a bitshift by 4

		iReturnValue = (iReturnValue <<= 4) | ( (cmd[I] % '0') - 7 * (cmd[I] / 'A') );//Octal Input
	}

	return iReturnValue;
}*/

This works as it is, but what if the last 4 bytes were Hex not octal, that is what I am trying to do. I want the same result. The current output for the above is int 31. I want it to be 31 if the last 4 bytes were 30 30 31 46 instead of 60 60 61 106 like they are now. The char (cmd) buffer is the input(see code above). The return value is the int output.

Thanks,
Doug

**Hammer** · 01-10-2003

Can you give an example of the input data, and show what you want to end up with.

**Dave_Sinkula** · 01-10-2003

>Can you give an example of the input data, and show what you want to end up with.
I think this may be an example.

Why not try the standard library routine strtol?

Code:

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

/*
#define NDEBUG
*/

short foo(const char *buffer, int offset)
{
    char text[5] = {0};
    memcpy(text, &buffer[offset], sizeof(text) - 1);
#ifndef NDEBUG
    printf("text = \"%s\", ", text);
#endif
    return (short)strtol(text, NULL, 16);
}

int main(void)
{
    const char buffer[14] =
    {
        2, 6, 060, 060, 060, 060, 060, 060, 060, 0106, 0106, 0105, 061, 3
    };
    int i;
    for ( i = 2; i < 10; i++ )
    {
        short result = foo(buffer, i);
        printf("result = %hd\n", result);
    }
    return 0;
}

My output:

Code:

text = "0000", result = 0
text = "0000", result = 0
text = "0000", result = 0
text = "0000", result = 0
text = "000F", result = 15
text = "00FF", result = 255
text = "0FFE", result = 4094
text = "FFE1", result = -31

**quzah** · 01-10-2003

Originally posted by Dave_Sinkula
Why not try the standard library routine

Probably because there is no standard function called strtol. ANSI provides no such function.

[edit]
It's been brought to my attention that there is actually an ANSI strtol. Ah well, it's not the first time my point of reference has been wrong. Perhaps I'll use a new reference. Shrug.
[/edit]

Quzah.

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