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10-14-2007, 01:27 AM
| #1 |
| Registered User Join Date: Oct 2007
Posts: 10
| File IO How can I keep retrieve hex value one by one of a file with the following contents 53 74 65 67 61 6E 6F 67 72 61 70 68 79 20 52 65 76 65 61 6C 65 64 0D 0A 4B 72 69 73 74 79 20 57 65 73 74 70 68 61 6C 20 32 30 30 33 2D 30 34 2D 30 39 0D 0A 4F 76 65 72 20 74 68 65 20 70 61 73 74 20 63 6F 75 70 6C 65 20 6F 66 20 79 65 61 72 73 2C 20 73 74 65 67 61 6E 6F 67 72 61 70 68 79 20 68 61 73 20 62 65 65 6E 20 74 68 65 20 73 6F 75 72 63 65 20 6F 66 20 61 20 6C 6F 74 20 6F 66 20 64 69 73 63 75 73 73 69 6F 6E 2C 20 70 61 72 74 69 63 75 6C 61 72 6C 79 20 61 73 20 69 74 20 77 61 73 20 73 75 73 70 65 63 74 65 64 20 74 68 61 74 20 74 65 72 72 6F 72 69 73 74 73 20 63 6F 6E 6E 65 63 74 65 64 20 77 69 74 68 20 74 68 65 20 53 65 70 74 65 6D 62 65 72 20 31 31 20 61 74 74 61 63 6B 73 20 6D 69 67 68 74 20 68 61 76 65 20 75 73 65 64 20 69 74 20 66 6F 72 20 63 6F 76 65 72 74 20 63 6F 6D 6D 75 6E 69 63 61 74 69 6F 6E 73 2E 20 57 68 69 6C 65 20 6E 6F 20 73 75 63 68 20 63 6F 6E 6E 65 63 74 69 6F 6E 20 68 61 73 20 62 65 65 6E 20 70 72 6F 76 65 6E 2C 20 74 68 65 20 63 6F 6E 63 65 72 6E 20 70 6F 69 6E 74 73 20 6F 75 74 20 74 68 65 20 65 66 66 65 63 74 69 76 65 6E 65 73 73 20 6F 66 20 73 74 65 67 61 6E 6F 67 72 61 70 68 79 20 61 73 20 61 20 6D 65 61 6E 73 20 6F 66 20 6F 62 73 63 75 72 69 6E 67 20 64 61 74 61 2E 20 49 6E 64 65 65 64 2C 20 61 6C 6F 6E 67 20 77 69 74 68 20 65 6E 63 72 79 70 74 69 6F 6E 2C 20 73 74 65 67 61 6E 6F 67 72 61 70 68 79 20 69 73 20 6F 6E 65 20 6F 66 20 74 68 65 20 66 75 6E 64 61 6D 65 6E 74 61 6C 20 77 61 79 73 20 62 79 20 77 68 69 63 68 20 64 61 74 61 20 63 61 6E 20 62 65 20 6B 65 70 74 20 63 6F 6E 66 69 64 65 6E 74 69 61 6C 2E 20 54 68 69 73 20 61 72 74 69 63 6C 65 20 77 69 6C 6C 20 6F 66 66 65 72 20 61 20 62 72 69 65 66 20 69 6E 74 72 6F 64 75 63 74 6F 72 79 20 64 69 73 63 75 73 73 69 6F 6E 20 6F 66 20 73 74 65 67 61 6E 6F 67 72 61 70 68 79 3A 20 77 68 61 74 20 69 74 20 69 73 2C 20 68 6F 77 20 69 74 20 63 61 6E 20 62 65 20 75 73 65 64 2C 20 61 6E 64 20 74 68 65 20 74 72 75 65 20 69 6D 70 6C 69 63 61 74 69 6F 6E 73 20 69 74 20 63 61 6E 20 68 61 76 65 20 6F 6E 20 69 6E 66 6F 72 6D 61 74 69 6F 6E 20 73 65 63 75 72 69 74 79 2E 0D 0A 0D 0A 57 68 61 74 20 69 73 20 53 74 65 67 61 6E 6F 67 72 61 70 68 79 3F 0D 0A 0D 0A 57 68 69 6C 65 20 77 65 20 61 72 65 20 64 69 73 63 75 73 73 69 6E 67 20 69 74 20 69 6E 20 74 65 72 6D 73 20 6F 66 20 63 6F 6D 70 75 74 65 72 20 73 65 63 75 72 69 74 79 2C 20 73 74 65 67 61 6E 6F 67 72 61 70 68 79 20 69 73 20 72 65 61 6C 6C 79 20 6E 6F 74 68 69 6E 67 20 6E 65 77 2C 20 61 73 20 69 74 20 68 61 73 20 62 65 65 6E 20 61 72 6F 75 6E 64 20 73 69 6E 63 65 20 74 68 65 20 74 69 6D 65 73 20 6F 66 20 61 6E 63 69 65 6E 74 20 52 6F 6D 65 2E 20 46 6F 72 20 65 78 61 6D 70 6C 65 2C 20 69 6E 20 61 6E 63 69 65 6E 74 20 52 6F 6D 65 20 61 6E 64 20 47 72 65 65 63 65 2C 20 74 65 78 74 20 77 61 73 20 74 72 61 64 69 74 69 6F 6E 61 6C 6C 79 20 77 72 69 74 74 65 6E 20 6F 6E 20 77 61 78 20 74 68 61 74 20 77 61 73 20 70 6F 75 72 65 64 20 6F 6E 20 74 6F 70 20 6F 66 20 73 74 6F 6E 65 20 74 61 62 6C 65 74 73 2E 20 49 66 20 74 68 65 20 73 65 6E 64 65 72 20 6F 66 20 74 68 65 20 69 6E 66 6F 72 6D 61 74 69 6F 6E 20 77 61 6E 74 65 64 20 74 6F 20 6F 62 73 63 75 72 65 20 74 68 65 20 6D 65 73 73 61 67 65 20 2D 20 66 6F 72 20 70 75 72 70 6F 73 65 73 20 6F 66 20 6D 69 6C 69 74 61 72 79 20 69 6E 74 65 6C 6C 69 67 65 6E 63 65 2C 20 66 6F 72 20 69 6E 73 74 61 6E 63 65 20 2D 20 74 68 65 79 20 77 6F 75 6C 64 20 75 73 65 20 73 74 65 67 61 6E 6F 67 72 61 70 68 79 3A 20 74 68 65 20 77 61 78 20 77 6F 75 6C 64 20 62 65 20 73 63 72 61 70 65 64 20 6F 66 66 20 61 6E 64 20 74 68 65 20 6D 65 73 73 61 67 65 20 77 6F 75 6C 64 20 62 65 20 69 6E 73 63 72 69 62 65 64 20 6F 72 20 77 72 69 74 74 65 6E 20 64 69 72 65 63 74 6C 79 20 6F 6E 20 74 68 65 20 74 61 62 6C 65 74 2C 20 77 61 78 20 77 6F 75 6C 64 20 74 68 65 6E 20 62 65 20 70 6F 75 72 65 64 20 6F 6E 20 74 6F 70 20 6F 66 20 74 68 65 20 6D 65 73 73 61 67 65 2C 20 74 68 65 72 65 62 79 20 6F 62 73 63 75 72 69 6E 67 20 6E 6F 74 20 6A 75 73 74 20 69 74 73 20 6D 65 61 6E 69 6E 67 20 62 75 74 20 69 74 73 20 76 65 72 79 20 65 78 69 73 74 65 6E 63 65 5B 31 5D 2E 20 0D 0A 41 63 63 6F 72 64 69 6E 67 20 74 6F 20 44 69 63 74 69 6F 6E 61 72 79 2E 63 6F 6D 2C 20 73 74 65 67 61 6E 6F 67 72 61 70 68 79 20 28 61 6C 73 6F 20 6B 6E 6F 77 6E 20 61 73 20 22 73 74 65 67 22 20 6F 72 20 22 73 74 65 67 6F 22 29 20 69 73 20 22 74 68 65 20 61 72 74 20 6F 66 20 77 72 69 74 69 6E 67 20 69 6E 20 63 69 70 68 65 72 2C 20 6F 72 20 69 6E 20 63 68 61 72 61 63 74 65 72 73 2C 20 77 68 69 63 68 20 61 72 65 20 6E 6F 74 20 69 6E 74 65 6C 6C 69 67 69 62 6C 65 20 65 78 63 65 70 74 20 74 6F 20 70 65 72 73 6F 6E 73 20 77 68 6F 20 68 61 76 65 20 74 68 65 20 6B 65 79 3B 20 63 72 79 70 74 6F 67 72 61 70 68 79 22 20 5B 32 5D 2E 20 49 6E 20 63 6F 6D 70 75 74 65 72 20 74 65 72 6D 73 2C 20 73 74 65 67 61 6E 6F 67 72 61 70 68 79 20 68 61 73 20 65 76 6F 6C 76 65 64 20 69 6E 74 6F 20 74 68 65 20 70 72 61 63 74 69 63 65 20 6F 66 20 68 69 64 69 6E 67 2 ? Thanks a lot I tried this, it didn't work very well. Code: char ch[4];
int t=0; //extract hex value
while (!inFile.eof())
{
inFile.getline(ch,4,' ');
sscanf(ch, "%x", &t);
}
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10-14-2007, 01:44 AM
| #2 |
| C++ Witch  Join Date: Oct 2003 Location: Singapore
Posts: 10,357
| This would be a simple example: Code: #include <iostream>
#include <fstream>
int main() {
std::ifstream in("hex.txt");
int num;
in >> std::hex; // Read in under hex representation.
while (in >> num)
{
std::cout << num << " ";
}
}
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10-14-2007, 04:26 AM
| #3 |
| Cat without Hat  Join Date: Apr 2003
Posts: 8,439
| That is, unless the file is in binary and you copied the contents from a hex editor.
__________________ All the buzzt!  CornedBee"There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code." - Flon's Law |
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10-14-2007, 07:33 AM
| #4 | |
| Registered User Join Date: Oct 2007
Posts: 10
| Quote:
my file is in binary *.bin. I open it with notepad but can only see garbage values. How do I extract the array of hex values from binary file as well ? Do i really have to find hex editor and copy the values to text file? No other ways? | |
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10-14-2007, 07:56 AM
| #5 |
| Cat without Hat Join Date: Apr 2003
Posts: 8,439
| No, that would be a supremely stupid way. I just wondered where the values from your post came from. To read a specific byte in a binary file, do this: Code: std::ifstream ifs(filename, std::ios_base::binary);
if(!ifs) {
// Opening failed.
}
char b;
ifs.read(&b, 1);
__________________ All the buzzt! CornedBee"There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code." - Flon's Law |
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10-14-2007, 06:48 PM
| #6 |
| Registered User Join Date: Oct 2007
Posts: 10
| Hi CornedBee, thanks for ur reply. when I use ur code, some bytes were appended with FFFFF in front. How do I solve such problem? |
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10-14-2007, 06:56 PM
| #7 |
| Deathray Engineer  Join Date: Mar 2007
Posts: 3,211
| What problem?
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10-14-2007, 07:47 PM
| #8 | |
| Registered User Join Date: Oct 2007
Posts: 10
| Quote:
I get 53 ffff74 fffff...other values | |
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10-14-2007, 08:39 PM
| #9 |
| Deathray Engineer Join Date: Mar 2007
Posts: 3,211
| Show your code.
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10-15-2007, 01:14 AM
| #10 |
| Cat without Hat Join Date: Apr 2003
Posts: 8,439
| He's casting the char to int, thus sign-extending some values. Do: Code: int widevalue = static_cast<int>(static_cast<unsigned char>(b));
__________________ All the buzzt! CornedBee"There is not now, nor has there ever been, nor will there ever be, any programming language in which it is the least bit difficult to write bad code." - Flon's Law |
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