As the title says, how do you read hex values using fstream?
i have this code: (let's say we have "FF" in the file.)
fstream infile;
infile.open(filename, fstream::in|fstream::out|fstream::app);
int a;
infile >> std::hex;
infile >> a;
cout << hex << a;but this does not give me any output instead of ff. I know there is a fscanf(fp, "%x", val) but I am curious is there any way to do this using stream library.
UPDATE:
My code was right all along, it turns out my error was I couldn't read "FFF" and put it in variable a,b,c like this
while (infile >> hex >> a >> b >> c) { cout << hex << a << b << c << "\n"; }Can somebody help me with this? do I have to separate every HEX values i want to read with space?
because infile >> hex >> setw(1) doesn't work..
4 Answers
You can use the hex modifier
int n;
cin >> hex >> n;This works:
int main()
{ const char *filename = "blah.txt"; ifstream infile(filename, fstream::in); unsigned int a; infile >> hex >> a; cout << hex << a;
}You have to chain std::hex when reading, the same way you chain it for writing :
infile >> std::hex >> a;Also make sure that your input file is written using a Hex editor and not a regular text editor. Otherwise a file foo.txt containing a character 'a' will be read as 0x61 and printed as 0x61 instead of 0xa. A nice Hex editor for linux is "Bless".
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