I got numbers from 0 to 999. How can I achieve the following
int i = 123;//possible values 0-999
char i_char[3] = /*do conversion of int i to char and add 3 leading zeros*/
Example(s): i_char shall look like "001" for i=1, "011" for i=11 or "101" for i=101
Use a std::ostringstream with std::setfill() and std::setw(), eg:
#include <string>
#include <sstream>
#include <iomanip>
int i = ...;
std::ostringstream oss;
oss << std::setfill('0') << std::setw(3) << i;
std::string s = oss.str();
It appears you are looking for sprintf, or perhaps printf.
int i = 123;
char str[10];
sprintf(str, "%03d", i);
Since, you tagged the question with c++ here is a quick solution using std::string and std::to_string:
#include <iostream>
#include <string>
int main() {
int i = 1;
std::string s = std::to_string(i);
if ( s.size() < 3 )
s = std::string(3 - s.size(), '0') + s;
std::cout << s << std::endl;
return 0;
}
For i=1 it will output: 001.
Related
I need to create file with specific file name format (on windows). the format is:
Name_nodeNum_frequency.txt
nodeNum is int and frequency is float.
those two variables should be written with fixed digits:
if nodeNum is 8 --> 008
if frequency is 4.88421 --> 4.884
this is the function:
create_file(int nodeNum, double frequency)
{
char buffer [50];
//convert int to string
itoa(nodeNum, buffer, 10);
string sNodeNum = string(buffer);
//not sure about the double
//tried to_string but I got:
// more than instance of overloaded function matches the argument list
string fileName = ("Name_" + sNodeNum + "_" + sfreq + "MHZ");
FILE* pFile = OpenFile(fileName);
}
I tried to use %d, but it seems like I should not do that:
string fileName = ("Delay_" + "%3d" + "_" + sfreq + "MHZ" , sNodeNum);
I will be happy for some guidance.
thanks!
You seem to be mixing C and C++ here. A simple way to do this in C would be:
#include <stdio.h>
int main()
{
int sNodeNum = 8;
double sfreq = 4.88421;
char filename[50];
sprintf(filename, "Delay_%03d_%.3fMHZ.txt", sNodeNum, sfreq);
FILE* pFile = fopen(filename, "w");
return 0;
}
If on the other hand, if you want to use C++, you should make a few changes:
#include <iomanip>
#include <fstream>
#include <sstream>
#include <iostream>
int main()
{
int sNodeNum = 8;
double sfreq = 4.88421;
std::ostringstream ss;
ss << "Delay_" << std::setfill('0') << std::setw(3) << sNodeNum
<< "_" << std::setprecision(4) << sfreq << "MHZ.txt";
std::string filename(ss.str());
std::ofstream fout(filename.c_str());
return 0;
}
Each of these two approaches opens a file for writing, with the name Delay_008_4.884MHZ.txt.
Live demo link
#include <string>
#include <iomanip>
#include <iostream>
int nodeNum = 8;
float frequency = 4.88421f;
std::ostream& out = std::cout; // put your std::ofstream file or std::ostringstream
std::ios::fmtflags flags = out.flags();
out.width(3);
out.fill('0');
out.setf(std::ios::right, std::ios::adjustfield);
out << nodeNum << std::endl;
flags = out.flags(flags);
out.precision(3);
out.setf(std::ios::fixed, std::ios::floatfield);
out << frequency;
out.flags(flags);
Or even simpler:
out << std::setw(3) << std::setfill('0') << std::right << nodeNum << std::endl;
out << std::setprecision(3) << std::fixed << frequency;
Output:
008
4.884
I have tried to count the numbers in a string but it doesnt work and I think it is logically good. I am a beginner in programming.
I know it works for one-digit numbers but that's intentional.
#include <iostream>
#include <string.h>
#include <vector>
using namespace std;
int main()
{
int numbs [10] = {0,1,2,3,4,5,6,7,8,9};
string str1;
cin >> str1;
vector <unsigned int> positions;
for (int a = 0 ;a <=10;a++)
{
int f = numbs[a];
string b = to_string(f);
unsigned pos = str1.find(b,0);
while(pos !=string::npos)
{
positions.push_back(pos);
pos = str1.find(b,pos+1);
break;
}
}
cout << "The count of numbers:" << positions.size() <<endl;
return 0;
}
If you need only to count digits in a string then there is no sense to use std::vector. You can count them without the vector. For example
#include <iostream>
#include <string>
int main()
{
std::string s( "A12B345C789" );
size_t count = 0;
for ( std::string::size_type pos = 0;
( pos = s.find_first_of( "0123456789", pos ) ) != std::string::npos;
++pos )
{
++count;
}
std::cout << "The count of numbers: " << count << std::endl;
return 0;
}
The output is
The count of numbers: 8
Also you could use standard algorithm std::count_if defined in header <algorithm>
For example
#include <iostream>
#include <string>
#include <algorithm>
#include <cctype>
int main()
{
std::string s( "A12B345C789" );
size_t count = std::count_if( s.begin(), s.end(),
[]( char c ) { return std::isdigit( c ); } );
std::cout << "The count of numbers: " << count << std::endl;
return 0;
}
The output is
The count of numbers: 8
If you need to count numbers instead of digits in a string then you should use standard C function strtol or C++ function std::stoi
Use substrings to extract every part of string with a delimiter(normally a space). Then convert each substring to number. The ones that qualify and converts probably are the numbers in your string. See how many you get.
You might also be interested in the C++ function "isdigit":
http://www.cplusplus.com/reference/locale/isdigit/
For example:
include <iostream>
#include <string.h>
#include <vector>
#include <locale> // std::locale, std::isdigit
using namespace std;
int main()
{
// Initialze array with count for each digit, 0 .. 9
int counts[10] = {0, 0, 0, 0, 0, 0, 0,0, 0, 0 };
int total = 0;
// Read input string
string str;
cin >> str;
// Parse each character in the string.
std::locale loc;
for (int i=0; i < str.length(); i++) {
if isdigit (str[i], loc) {
int idx = (int)str[i];
counts[idx]++
total++;
}
// Print results
cout << "The #/digits found in << str << " is:" << total << endl;
// If you wanted, you could also print the total for each digit ...
return 0;
}
I'm loosing my mind at the moment and below is what I'm trying to do.
char* buffer;
sprintf(buffer, "0x%08x", 5);
*(int *)(0x834AF2AC + 0x1a) = ?buffer?;
Buffer = 0x05000000
I need to set that in memory, if I just set 05 it will set 0x00000005
Question asked better.
How can I convert an INT into a format of "0x%08x"
So 5 becomes 0x05000000
ANSWERD:
The correct answer is *(int *)(0x834AF2AC + 0x1a) = 5<<24;
Something like this:
#include <iostream> // for std::cout, std::endl
#include <string> // for std::string, std::stoi
int main()
{
std::string s{"0x05"};
int i = std::stoi(s, nullptr, 16); // convert base 16 number in s to int
std::cout << i << std::endl;
}
Two result from google which points to stackoverflow (result 1 and 2).
Convert char to int in C and C++
C char* to int conversion
I'm not sure if I understand correctly but if you want to convert an entire string to int, then I would suggest stringstream.
http://www.cplusplus.com/reference/sstream/stringstream/stringstream/
For hexadecimal string:
#include <string> // std::string
#include <iostream> // std::cout
#include <sstream> // std::stringstream
int main () {
std::stringstream ss;
ss << std::hex << 0x05;
int foo;
ss >> foo;
std::cout << "foo: " << foo << '\n';
return 0;
}
I am looking for a fastest way to convert a byte array of arbitrary length to a hexadecimal string. This question has been fully answered here at StackOverflow for C#. Some solutions in C++ can be found here.
Are there any "turnkey" or "ready-made" solutions to a problem? C-style solutions are welcome.
#include <vector>
#include <iostream>
#include <algorithm>
#include <string>
#include <iterator>
#include <sstream>
#include <iomanip>
int main()
{
std::vector<unsigned char> v;
v.push_back( 1 );
v.push_back( 2 );
v.push_back( 3 );
v.push_back( 4 );
std::ostringstream ss;
ss << std::hex << std::uppercase << std::setfill( '0' );
std::for_each( v.cbegin(), v.cend(), [&]( int c ) { ss << std::setw( 2 ) << c; } );
std::string result = ss.str();
std::cout << result << std::endl;
return 0;
}
Or, if you've got a compiler that supports uniform initialization syntax and range based for loops you can save a few lines.
#include <vector>
#include <sstream>
#include <string>
#include <iostream>
#include <iomanip>
int main()
{
std::vector<unsigned char> v { 1, 2, 3, 4 };
std::ostringstream ss;
ss << std::hex << std::uppercase << std::setfill( '0' );
for( int c : v ) {
ss << std::setw( 2 ) << c;
}
std::string result = ss.str();
std::cout << result << std::endl;
}
Use boost::alogorithm::hex
std::vector<unsigned char> v;
v.push_back(1);
v.push_back(2);
v.push_back(3);
v.push_back(4);
std::string res;
boost::algorithm::hex(v.begin(), v.end(), back_inserter(res));
You can use the C++ Standard Library and or you can use boost::lexical_cast
#include <iostream>
#include <string>
#include <array>
#include <vector>
#include <sstream>
#include <iomanip>
#include <algorithm>
using namespace std;
// use this macro for c++11 feature
#define USE_CPP11
int main(int argc, char* argv[])
{
array<unsigned char, 3> hexArr = {0x01, 0xff, 0x55};
const char separator = ' '; // separator between two numbers
ostringstream os;
os << hex << setfill('0'); // set the stream to hex with 0 fill
#ifdef USE_CPP11
std::for_each(std::begin(hexArr), std::end(hexArr), [&os, &separator] (int i)
{
os << setw(2) << i << separator;
});
#else // c++03
typedef array<unsigned char, 3>::const_iterator const_iterator;
for (const_iterator it = hexArr.begin(); it != hexArr.end(); ++it)
{
os << setw(2) << int(*it) << separator;
}
#endif
os << dec << setfill(' '); // reset the stream to "original"
// print the string
cout << "the string array is: " << os.str() << endl;
return EXIT_SUCCESS;
}
One of the fastest way I know in C++ 11:
template <size_t byteCount>
string BytesArrayToHexString( const std::array<byte, byteCount>& src )
{
static const char table[] = "0123456789ABCDEF";
std::array<char, 2 * byteCount + 1> dst;
const byte* srcPtr = &src[0];
char* dstPtr = &dst[0];
for (auto count = byteCount; count > 0; --count)
{
unsigned char c = *srcPtr++;
*dstPtr++ = table[c >> 4];
*dstPtr++ = table[c & 0x0f];
}
*dstPtr = 0;
return &dst[0];
}
A good compiler should not have any problem to apply SSE optimization on this....
I would like to know what is the easiest way to convert an int to C++ style string and from C++ style string to int.
edit
Thank you very much. When converting form string to int what happens if I pass a char string ? (ex: "abce").
Thanks & Regards,
Mousey
Probably the easiest is to use operator<< and operator>> with a stringstream (you can initialize a stringstream from a string, and use the stream's .str() member to retrieve a string after writing to it.
Boost has a lexical_cast that makes this particularly easy (though hardly a paragon of efficiency). Normal use would be something like int x = lexical_cast<int>(your_string);
You can change "%x" specifier to "%d" or any other format supported by sprintf. Ensure to appropriately adjust the buffer size 'buf'
int main(){
char buf[sizeof(int)*2 + 1];
int x = 0x12345678;
sprintf(buf, "%x", x);
string str(buf);
int y = atoi(str.c_str());
}
EDIT 2:
int main(){
char buf[sizeof(int)*2 + 1];
int x = 42;
sprintf(buf, "%x", x);
string str(buf);
//int y = atoi(str.c_str());
int y = static_cast<int>(strtol(str.c_str(), NULL, 16));
}
This is to convert string to number.
#include "stdafx.h"
#include <iostream>
#include <string>
#include <sstream>
int convert_string_to_number(const std::string& st)
{
std::istringstream stringinfo(st);
int num = 0;
stringinfo >> num;
return num;
}
int main()
{
int number = 0;
std::string number_as_string("425");
number = convert_string_to_number(number_as_string);
std::cout << "The number is " << number << std::endl;
std::cout << "Number of digits are " << number_as_string.length() << std::endl;
}
Like wise, the following is to convert number to string.
#include "stdafx.h"
#include <iostream>
#include <string>
#include <sstream>
std::string convert_number_to_string(const int& number_to_convert)
{
std::ostringstream os;
os << number_to_convert;
return (os.str());
}
int main()
{
int number = 425;
std::string stringafterconversion;
stringafterconversion = convert_number_to_string(number);
std::cout << "After conversion " << stringafterconversion << std::endl;
std::cout << "Number of digits are " << stringafterconversion.length() << std::endl;
}
Use atoi to convert a string to an int. Use a stringstream to convert the other way.