This question already has answers here:
Converting a hex string to a byte array
(22 answers)
Closed 5 years ago.
I have string hex ex.
std :: string x="68656c6c6f" ;
I want to convert it to array of characters
each element in the array is 2 hexadecimal numbers
ex.
char c[5]={0x68,0x65,0x6c,0x6c,0x6f} ;
I'm using c++, and I already have the string of hexadecimal numbers and I don't have the option to read the values as an array of character.
I can't use scanf("%x",&c[i]);
C (will work in C++ as well)
int cnvhex(const char *num, int *table)
{
const char *ptr;
int index = (num == NULL || table == NULL) * -1;
size_t len = strlen(num);
ptr = num + len - 2;
if (!index)
{
for (index = 0; index < len / 2; index++)
{
char tmp[3] = { 0, };
strncpy(tmp, ptr, 2);
if (sscanf(tmp, "%x", table + index) != 1)
{
index = -1;
break;
}
ptr -= 2;
}
if (index != -1 && (len & 1))
{
char tmp[2] = { *num, 0};
if(sscanf(tmp, "%x", table + index++) != 1) index = -1;
}
}
return index;
}
Related
I have below function that supports for conversion of LPCTSTR to BYTE , but the input str only support digits as of now.
void StrToByte2(LPCTSTR str, BYTE *dest)
{
UINT count = _ttoi(str);
BYTE buf[4] = { 0 };
char string[10] = { 0 };
sprintf_s(string, 10, "%04d", count);
for (int i = 0; i < 4; ++i)
{
if ((string[i] >= '0') && (string[i] <= '9'))
buf[i] = string[i] - '0';
}
dest[0] = (BYTE)(buf[0] << 4) | buf[1];
dest[1] = (BYTE)(buf[2] << 4) | buf[3];
}
If i call this function on "1234" ( any digits) , dest output some 12814,
struct st
{
byte btID[2];
int nID;
};
PTR ptr(new st);
StrToByte2(strCode, ptr->btID);
but when i call this function on any hexadecimal ex A123 , it outputs 0000 always.
Below function is used to convert back the dest code to str
CString Byte2ToStr(const byte* pbuf)
{
CString str;
str.Format(_T("%02X%02X"), pbuf[0], pbuf[1]);
return str;
}
How can i get A123 to converted to bytes and than back to str to display A123??
Please help!!
PTR ptr(new st);
This is a memory leak in C++, because new st allocates memory and there is no way to release it.
UINT count = _ttoi(str);
...
sprintf_s(string, 10, "%04d", count);
This is converting string to integer, then converts integer back to string. It doesn't seem to have a real purpose.
For example, "1234" is converted to 1234, and back to "1234". But "A123" is not a valid number so it is converted to 0, then converted to "0000". So this method fails. You can just work with the original string.
It seems this function tries to fit 2 integers in to 1 byte. This can be done as long as each value is less than 16 or 0xF (I don't know what purpose this might have) It can be fixed as follows:
void StrToByte2(const wchar_t* str, BYTE *dest)
{
int len = wcslen(str);
if(len != 4)
return; //handle error
char buf[4] = { 0 };
for(int i = 0; i < 4; ++i)
if(str[i] >= L'0' && str[i] <= L'9')
buf[i] = (BYTE)(str[i] - L'0');
dest[0] = (buf[0] << 4) + buf[1];
dest[1] = (buf[2] << 4) + buf[3];
}
CStringW Byte2_To_Str(BYTE *dest)
{
CStringW str;
str.AppendFormat(L"%X", 0xF & (dest[0] >> 4));
str.AppendFormat(L"%X", 0xF & (dest[0]));
str.AppendFormat(L"%X", 0xF & (dest[1] >> 4));
str.AppendFormat(L"%X", 0xF & (dest[1]));
return str;
}
int main()
{
BYTE dest[2] = { 0 };
StrToByte2(L"1234", dest);
OutputDebugStringW(Byte2_To_Str(dest));
OutputDebugStringW(L"\n");
return 0;
}
If the string is hexadecimal, you can use sscanf to convert each pair of character to bytes.
Basically, "1234" changes to 12 34
"A123" changes to A1 23
bool hexstring_to_bytes(const wchar_t* str, BYTE *dest, int dest_size = 2)
{
int len = wcslen(str);
if((len / 2) > dest_size)
{
//error
return false;
}
for(int i = 0; i < len / 2; i++)
{
int v;
if(swscanf_s(str + i * 2, L"%2x", &v) != 1)
break;
dest[i] = (unsigned char)v;
}
return true;
}
CStringW bytes_to_hexstring(const BYTE* bytes, int byte_size = 2)
{
CString str;
for(int i = 0; i < byte_size; i++)
str.AppendFormat(L"%02X ", bytes[i] & 0xFF);
return str;
}
int main()
{
CStringW str;
CStringW new_string;
BYTE dest[2] = { 0 };
str = L"1234";
hexstring_to_bytes(str, dest);
new_string = bytes_to_hexstring(dest);
OutputDebugString(new_string);
OutputDebugString(L"\n");
str = L"A123";
hexstring_to_bytes(str, dest);
new_string = bytes_to_hexstring(dest);
OutputDebugStringW(new_string);
OutputDebugStringW(L"\n");
return 0;
}
I'm new to C++ and our teacher asked us to get a function that does the above title. So far I've got a function that converts a string to an integer, but I have no idea about how to modify it to make it work if the numbers in the string would represent a float.
int convert(char str[], int size) {
int number = 0;
for (int i = 0; i < size; ++i) {
number += (str[i] - 48)*pow(10, (size - i - 1));
}
return number;
}
If I run:
char myString[] = "12345";
convert(myString, 5);
I get:
12345
But if I run:
char myString[] = "123.45";
convert(myString, 5);
I get:
122845
How could I modify my program to work with floats too? I know convert function is meant to return an int so, should I use two more functions?
I was thinking about one that determinates if the string is inteded to be converted to an integer or a string, and the other that'll actually convert the string to a float.
Here is the function for doing so...
template<class T, class S>
T convert_string_to_number(S s)
{
auto result = T(0.l);
if (s.back() == L'F' || s.back() == L'f')
s = s.substr(0u, s.size() - 1u);
auto temp = s;
auto should_add = false;
if (!std::is_floating_point<T>::value)
{
should_add = temp.at(temp.find_first_of(L'.') + 1) >= '5';
temp.erase(temp.begin() + temp.find_first_of(L'.'), temp.end());
}
else if (temp.find_first_of(L'.') != S::npos)
temp.erase(temp.begin() + temp.find_first_of(L'.'));
for (int i = temp.size() - 1u; i >= 0; --i)
if (temp[i] >= L'0' && temp[i] <= L'9')
result += T(std::powl(10.l, temp.size() - i - 1.l) * (temp[i] - L'0'));
else
throw std::invalid_argument("Invalid numerical string!");
if (s.find(L'-') != S::npos)
result = -T(std::fabs(result));
if (s.find(L'.') != S::npos && std::is_floating_point<T>::value)
result /= T(std::powl(10.l, s.size() - s.find(L'.') - 1.l));
return std::is_floating_point<T>::value ? T(result) : T(result + T(should_add));
}
Just use it like you typically would...
auto some_number = convert_string_to_number<float>(myString);...
For the floating point part of the assignment: what about regular expressions? It is also kind of built-in functionality, but general purpose, not designed for your particular task, so I hope your teacher will be fine with this idea.
You can use the following regex: [+-]?([0-9]*[.])?[0-9]+ (I got it from this answer) to detect if provided string is a floating point number. Then you can modify the expression a little bit to capture the +/- signs and parts before/after the dot separator. Once you extract these features the task should be relatively simple.
Also please change your method signature to: float convert(const std::string& str).
Try this :
int convert(char str[], int size) {
int number = 0;
for (int i = 0; i < size; ++i) {
number += (str[i] - 48)*pow(10, (size - i - 1));
}
return number;
}
int pow10(int radix)
{
int r = 1;
for (int i = 0; i < radix; i++)
r *= 10;
return r;
}
float convert2float(char str[], int size) { //size =6
// convert to string_without_decimal
char str_without_decimal[10];
int c = 0;
for (int i = 0; i < size; i++)
{
if (str[i] >= 48 && str[i] <= 57) {
str_without_decimal[c] = str[i];
c++;
}
}
str_without_decimal[c] = '\0'; //str_without_decimal = "12345"
//adjust size if dot present or not. If no dot present => size = c
size = (size != c ?) size - 1 : size; //size = 5 = 6-1 since dot is present
//convert to decimal
int decimal = convert(str_without_decimal, size); //decimal = 12345
//get divisor
int i;
for (i = size; i >= 0; i--) {
if (str[i] == '.') break;
}
int divisor = pow10(size - i); //divisor = 10;
return (float)decimal/(float) divisor; // result = 12345 /10
}
int main()
{
char str[] = "1234.5";
float f = convert2float(str, 6);
cout << f << endl;
return 0;
}
I'am doing DNS lookup tool in C++ and i am trying to get IPv6 from
unsigned char * (where it is stored in non readable format), copy it to struct in6_addr, then i want to convert it and print it.
struct in6_addr tmp2;
char buf[41];
memcpy(tmp2.s6_addr, answ[i].rdata, 128);
cout << answ[i].name << " IN AAAA " << inet_ntop(AF_INET6, tmp2.s6_addr, buf, 128) << endl;
My output should look like this,
www.domain.name.cz. IN AAAA 2001:67c:1220:809::93e5:917
but somehow it looks like this.
www.domain.name.cz IN AAAA 106:7c12:2008:900::
Generating RDATA
u_char *ReadName(unsigned char *readResponse, unsigned char *buffer, int *count) {
unsigned char *name;
unsigned int p = 0, jumped = 0, offset;
int i, j;
*count = 1;
name = (unsigned char *) malloc(256);
name[0] = '\0';
//read the names in 3www6google3com format
while (*readResponse != 0) {
if (*readResponse >= 192) {
offset = (*readResponse) * 256 + *(readResponse + 1) - 49152; //49152 = 11000000 00000000 ;)
readResponse = buffer + offset - 1;
jumped = 1; //we have jumped to another location so counting wont go up!
} else {
name[p++] = *readResponse;
}
readResponse = readResponse + 1;
if (jumped == 0) {
*count = *count + 1; //if we havent jumped to another location then we can count up
}
}
name[p] = '\0'; //string complete
if (jumped == 1) {
*count = *count + 1; //number of steps we actually moved forward in the packet
}
//now convert 3www6google3com0 to www.google.com
for (i = 0; i < (int) strlen((const char *) name); i++) {
p = name[i];
for (j = 0; j < (int) p; j++) {
name[i] = name[i + 1];
i = i + 1;
}
name[i] = '.';
}
name[i - 1] = '\0'; //remove the last dot
return name;
Thanks for your help!
This question already has answers here:
Convert two ASCII Hexadecimal Characters (Two ASCII bytes) in one byte
(6 answers)
Closed 6 years ago.
I have a typical use case where i need to convert the unsigned char values to hexadecimal.
For example,
unsigned char *pBuffer = (unsigned char *)pvaluefromClient //where pvaluefromclient is received from a client
The length of pBuffer is 32 bytes and it holds the value as follows,
(gdb) p pBuffer
$5 = (unsigned char *) 0x7fd4b82cead0 "EBA5F7304554DCC3702E06182AB1D487"
(gdb) n
STEP 1: I need to split this pBuffer value as follows,
{EB,A5,F7,30,45,54,DC,C3,70,2E,06,18,2A,B1,D4,87 }
STEP 2: I need to convert the above splited values to decimal as follows,
const unsigned char pConvertedBuffer[16] = {
235,165,247,48,69,84,220,195,112,46,6,24,42,177,212,135
};
Any idea on how to achieve the STEP1 and STEP2? any help on this would be highly appreciated
How about something like this:
unsigned char *pBuffer = (unsigned char *)pvaluefromClient //where valuefromclient is received from a client
int i, j;
unsigned char target[16]
for(i=0;i<32;i+=2)
{
sscanf((char*)&pBuffer[i], "%02X", &j);
target[i/2] = j;
}
You can create a function that takes two unsigned chars as parameter and returns another unsigned char. The two parameters are the chars (E and B for the first byte). The returned value would be the numerical value of the byte.
The logic would be :
unsigned char hex2byte(unsigned char uchar1, unsigned char uchar2) {
unsigned char returnValue = 0;
if((uchar1 >= '0') && (uchar1 <= '9')) {
returnValue = uchar1 - 0x30; //0x30 = '0'
}
else if((uchar1 >= 'a') && (uchar1 <= 'f')) {
returnValue = uchar1 - 0x61 + 0x0A; //0x61 = 'a'
}
else if((uchar1 >= 'A') && (uchar1 <= 'F')) {
returnValue = uchar1 - 0x41 + 0x0A; //0x41 = 'A'
}
if((uchar2 >= '0') && (uchar2 <= '9')) {
returnValue = (returnValue <<8) + (uchar2 - 0x30); //0x30 = '0'
}
else if((uchar2 >= 'a') && (uchar2 <= 'f')) {
returnValue = (returnValue <<8) + (uchar2 - 0x61 + 0x0A); //0x61 = 'a'
}
else if((uchar2 >= 'A') && (uchar1 <= 'F')) {
returnValue = (returnValue <<8) + (uchar2 - 0x41 + 0x0A); //0x41 = 'A'
}
return returnValue;
}
The basic idea is to calculate the numerical value of the chars and to reassemble a number from two chars (hence the bit shift)
I'm pretty sure there are multiple more elegant solutions than mine here and there.
void Conversion(char *pBuffer, int *ConvertedBuffer)
{
int j = 0;
for(int i = 0; i < 32; i += 2)
{
std::stringstream ss;
char sz[4] = {0};
sz[0] = pBuffer[i];
sz[1] = pBuffer[i+1];
sz[2] = 0;
ss << std::hex << sz;
ss >> ConvertedBuffer[j];
++j;
}
}
int main()
{
char Buffer[] = "EBA5F7304554DCC3702E06182AB1D487";
int ConvertedBuffer[16];
Conversion(Buffer, ConvertedBuffer);
for(int i = 0; i < 16; ++i)
{
cout << ConvertedBuffer[i] << " ";
}
return 0;
}
//output:
235 165 247 48 69 84 220 195 112 46 6 24 42 177 212 135
This is a function in c++ that takes a HEX string and converts it to its equivalent ASCII character.
string HEX2STR (string str)
{
string tmp;
const char *c = str.c_str();
unsigned int x;
while(*c != 0) {
sscanf(c, "%2X", &x);
tmp += x;
c += 2;
}
return tmp;
If you input the following string:
537461636b6f766572666c6f77206973207468652062657374212121
The output will be:
Stackoverflow is the best!!!
Say I were to input 1,000,000 unique HEX strings into this function, it takes awhile to compute.
Is there a more efficient way to complete this?
Of course. Look up two characters at a time:
unsigned char val(char c)
{
if ('0' <= c && c <= '9') { return c - '0'; }
if ('a' <= c && c <= 'f') { return c + 10 - 'a'; }
if ('A' <= c && c <= 'F') { return c + 10 - 'A'; }
throw "Eeek";
}
std::string decode(std::string const & s)
{
if (s.size() % 2) != 0) { throw "Eeek"; }
std::string result;
result.reserve(s.size() / 2);
for (std::size_t i = 0; i < s.size() / 2; ++i)
{
unsigned char n = val(s[2 * i]) * 16 + val(s[2 * i + 1]);
result += n;
}
return result;
}
Just since I wrote it anyway, this should be fairly efficient :)
const char lookup[32] =
{0,10,11,12,13,14,15,0,0,0,0,0,0,0,0,0,0,1,2,3,4,5,6,7,8,9,0,0,0,0,0,0};
std::string HEX2STR(std::string str)
{
std::string out;
out.reserve(str.size()/2);
const char* tmp = str.c_str();
unsigned char ch, last = 1;
while(*tmp)
{
ch <<= 4;
ch |= lookup[*tmp&0x1f];
if(last ^= 1)
out += ch;
tmp++;
}
return out;
}
Don't use sscanf. It's a very general flexible function, which means its slow to allow all those usecases. Instead, walk the string and convert each character yourself, much faster.
This routine takes a string with (what I call) hexwords, often used in embedded ECUs, for example "31 01 7F 33 38 33 37 30 35 31 30 30 20 20 49" and transforms it in readable ASCII where possible.
Transforms by taking care of the discontuinity in the ASCII table (0-9: 48-57, A-F:65 - 70);
int i,j, len=strlen(stringWithHexWords);
char ascii_buffer[250];
char c1, c2, r;
i=0;
j=0;
while (i<len) {
c1 = stringWithHexWords[i];
c2 = stringWithHexWords[i+1];
if ((int)c1!=32) { // if space found, skip next section and bump index only once
// skip scary ASCII codes
if (32<(int)c1 && 127>(int)c1 && 32<(int)c2 && 127>(int)c2) {
//
// transform by taking first hexdigit * 16 and add second hexdigit
// both with correct offset
r = (char) ((16*(int)c1+((int)c2<64?((int)c2-48):((int)c2-55))));
if (31<(int)r && 127>(int)r)
ascii_buffer[j++] = r; // check result for readability
}
i++; // bump index
}
i++; // bump index once more for next hexdigit
}
ascii_bufferCurrentLength = j;
return true;
}
The hexToString() function will convert hex string to ASCII readable string
string hexToString(string str){
std::stringstream HexString;
for(int i=0;i<str.length();i++){
char a = str.at(i++);
char b = str.at(i);
int x = hexCharToInt(a);
int y = hexCharToInt(b);
HexString << (char)((16*x)+y);
}
return HexString.str();
}
int hexCharToInt(char a){
if(a>='0' && a<='9')
return(a-48);
else if(a>='A' && a<='Z')
return(a-55);
else
return(a-87);
}