c++ convert string to hex

Question

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C++ convert hex string to signed integer

I allready searched on google but didn't find any help. So heres my problem: I have strings that allready contains hex code e.g.: string s1 = "5f0066" and i want to convert this string to hex. I need to compare the string with hex code i've read in a binary file.

(Just need the basic idea how to convert the string) 5f Best regards and thanks.

Edit: Got the binary file info in the format of unsigned char. SO its 0x5f... WOuld like to have teh string in the same format

What does mean "want to convert this string to hex" if they already are in hex? — Alessandro Pezzato, Jul 23 '12 at 08:30
`strtol()` from ``? Just guessing, your question is not very clear. — DevSolar, Jul 23 '12 at 08:31
In case you read these strings from file (specifically, from `std::ifstream`), [this](http://stackoverflow.com/questions/5555849/reading-hex-values-from-fstream-into-int) may be a better answer than the duplicate question posted above. — jogojapan, Jul 23 '12 at 08:33

score 17 · Answer 1 · edited Feb 12 '19 at 05:43

17

Use std:stoi as (in C++11 only):

std::string s = "5f0066";
int num = std::stoi(s, 0, 16);

Online demo

edited Feb 12 '19 at 05:43

congusbongus

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answered Jul 23 '12 at 08:36

Nawaz

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An unsigned integer such as 0xffeeddcc will probably throw std::out_of_range. Fix: use std::stoul – Sundae Jan 21 '15 at 12:14
2

If the string is too long, it won't convert to a correct number (int can't hold so much). I don't really like this answer. – David 天宇 Wong Aug 16 '16 at 01:59

score 14 · Answer 2 · edited Aug 27 '17 at 17:15

14

Use stringstream and std::hex

std::stringstream str;
std::string s1 = "5f0066";
str << s1;
int value;
str >> std::hex >> value;

edited Aug 27 '17 at 17:15

Community

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answered Jul 23 '12 at 08:34

Yochai Timmer

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I got the folowing: 1500-030: (I) INFORMATION: std::num_get > >::_Getffld(char *, istreambuf_iterator > &, istreambuf_iterator > &, const locale &): Additional optimization may be attained by recompiling and specifying MAXMEM option with a value greater than 8192. – Vincent Guyard Mar 01 '18 at 21:08

score 7 · Answer 3 · answered Jul 23 '12 at 08:33

7

strtol(str, NULL, 16) or strtoul(str, NULL, 16) should do what you need.

strtol strtoul

answered Jul 23 '12 at 08:33

CygnusX1

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c++ convert string to hex

3 Answers3

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