Im trying to write a program to parse a list of hex strings. Each hex string is 2 bytes and represents a two complements number. I need a fast and efficient way to convert this to a integer. Files containing the hex string are 30-100mb so i need something very efficient. if someone can help me out that would be great.
THX
A function that could convert hex to integer is strtol, I think.
Originally Posted by Adak
strtol() is probably the fastest way to do one number, as Elysia already suggested.
However, if you know how many numbers to read and in what format, one of the family of scanf() function might be better.... but be aware of the issues of using scanf().
Yep you have big files sizes. So what do you mean by being efficient? I feel that reading such big files will take bigger fractions of your time. So stop worrying about efficient converter function.
/* Some one will be ready for knit picking. */
I believe your emphasis on efficiency is mis-guided.
If you haven't timed or profiled working code, how do you know you even have an efficiency problem?
Your bottleneck should be your HD reading the data.
In any case, show us your code where you have tried this, and let's see what's needed. Don't just drop the "I need a program to do this and that, and it really needs to be efficient, too", post on us, and expect a program served up on a silver platter.
Our butler has retired.
Well i took this lookup table code form somewhere and modified it a bit
Code:signed short parseHex(char *value) { int i,j; typedef struct { char chr; signed short value; } CHexMap; int HexMapL = 16; CHexMap HexMap[] = { {'0', 0}, {'1', 1}, {'2', 2}, {'3', 3}, {'4', 4}, {'5', 5}, {'6', 6}, {'7', 7}, {'8', 8}, {'9', 9}, {'A', 10}, {'B', 11}, {'C', 12}, {'D', 13}, {'E', 14}, {'F', 15} }; signed short result = 0; char *s = value; for (j = 0; j < 4; j++) { result << 4; for (i = 0; i < HexMapL; i++) { if (*s == HexMap[i].chr) { result |= HexMap[i].value; break; } } s++; } return result; }
