We Keep Coding

Not able to connect in socket programming in C++ whereas in python, it works

I have a piece of code in python. It is related to client Socket programming. I want to get the NTRIP data from "www.rtk2go.com". The code written in python works well and serves the purpose.
import socket
import base64
server = "www.rtk2go.com"
port = "2101"
mountpoint = "leedgps"
username = ""
password = ""
def getHTTPBasicAuthString(username, password):
inputstring = username + ':' + password
pwd_bytes = base64.standard_b64encode(inputstring.encode("utf-8"))
pwd = pwd_bytes.decode("utf-8").replace('\n', '')
return pwd
pwd = getHTTPBasicAuthString(username, password)
print(pwd)
header = "GET /{} HTTP/1.0\r\n".format(mountpoint) + \
"User-Agent: NTRIP u-blox\r\n" + \
"Accept: */*\r\n" + \
"Authorization: Basic {}\r\n".format(pwd) + \
"Connection: close\r\n\r\n"
print(header)
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect((server, int(port)))
s.sendto(header.encode('utf-8'), (server, int(port)))
resp = s.recv(1024)
try:
while True:
try:
data = s.recv(2048)
except:
pass
finally:
s.close()
I wanted to implement the same thing in c++ code and after going through few online tutorials, I wrote the following code in C++ (I am very new to C++)
#include <iostream>
#include <stdio.h>
#include <sys/socket.h>
#include <arpa/inet.h>
#include <string.h>
#include <netdb.h>
using namespace std;
#define SIZE 1000
#define PORT 2101
string base64Encoder(string input_str, int len_str) {
char char_set[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
char *res_str = (char *) malloc(SIZE * sizeof(char));
int index, no_of_bits = 0, padding = 0, val = 0, count = 0, temp;
int i, j, k = 0;
for (i = 0; i < len_str; i += 3) {
val = 0, count = 0, no_of_bits = 0;
for (j = i; j < len_str && j <= i + 2; j++) {
val = val << 8;
val = val | input_str[j];
count++;
}
no_of_bits = count * 8;
padding = no_of_bits % 3;
while (no_of_bits != 0) {
// retrieve the value of each block
if (no_of_bits >= 6) {
temp = no_of_bits - 6;
// binary of 63 is (111111) f
index = (val >> temp) & 63;
no_of_bits -= 6;
} else {
temp = 6 - no_of_bits;
// append zeros to right if bits are less than 6
index = (val << temp) & 63;
no_of_bits = 0;
}
res_str[k++] = char_set[index];
}
}
for (i = 1; i <= padding; i++) {
res_str[k++] = '=';
}
res_str[k] = '\0';
string a = res_str;
return a;
}
int main() {
string input_str = ":";
int len_str;
len_str = input_str.length();
string pwd = base64Encoder(input_str, len_str);
string mountpoint = "leedgps";
string header = "GET /" + mountpoint + " HTTP/1.0\r\n" + \
"User-Agent: NTRIP u-blox\r\n" + \
"Accept: */*\r\n" + \
"Authorization: Basic " + pwd + "\r\n" + \
"Connection: close\r\n\r\n";
struct hostent *h;
if ((h = gethostbyname("www.rtk2go.com")) == NULL) { // Lookup the hostname
cout << "cannot look up hostname" << endl;
}
struct sockaddr_in saddr;
int sockfd, connfd;
sockfd = socket(AF_INET, SOCK_STREAM, 0) < 0;
if (sockfd) {
printf("Error creating socket\n");
}
saddr.sin_family = AF_INET;
saddr.sin_port = htons(2101);
if(inet_pton(AF_INET, "3.23.52.207", &saddr.sin_addr)<=0) //
{
printf("\nInvalid address/ Address not supported \n");
return -1;
}
cout << connect(sockfd, (struct sockaddr *)&saddr, sizeof(saddr)) << endl;
return 0;
}
But the connect method always returns -1 (in C++). Any idea what am I doing wrong?

sockfd = socket(AF_INET, SOCK_STREAM, 0) < 0;
means that sockfd is either 0 or 1, which is not a valid socket.
Do this instead:
sockfd = socket(AF_INET, SOCK_STREAM, 0);
if (sockfd < 0) {
printf("Error creating socket\n");
}

python script slowing down and almost stops after a couple of seconds

I am trying to make a resource monitor with an arduino and it is working great for almost 20 seconds before it almost stops running.
When it slows down, it takes almost 5 seconds between updates.
I have tried to comment out everything with psutil and giving it a permanent value.
and have tried the same with GPUtil.
Here is the python code
import serial.tools.list_ports
import serial
import psutil
import GPUtil
import time
import serial
ports = list(serial.tools.list_ports.comports())
baud = 9600
for p in ports:
if "Arduino" in p[1]:
port = p[0]
ser=serial.Serial(port, baud, timeout=1)
try:
while True:
cpuUsage = psutil.cpu_percent()
ramUsage = psutil.virtual_memory()
cpuUsage = str(cpuUsage)
GPUs = GPUtil.getGPUs()
gpuUsage = GPUs[0].load
gpuUsage = str(gpuUsage)
gpuUsage = gpuUsage[2:]
ramUsage = str(ramUsage.percent)
toSend = cpuUsage + "," + gpuUsage + ","+ ramUsage
print (toSend)
ser.write(toSend.encode())
#print("20.5".encode())
#line = ser.readline()[:-2]
#line.decode()
#print ("Read : " , line);
time.sleep(0.1)
except:
print ("error")
Here is the Arduino code
#include <FastLED.h>
#define NUM_LEDS 15
#define DATA_PIN 6
float Cpu = 40;
float Gpu = 99;
float Ram = 60;
String Cpu_Read;
String Gpu_Read;
String Ram_Read;
int RXLED = 17;
String StrNumbers = "";
int numbers;
int Received = 0;
int Separrator = 0;
String Text = "";
CRGB leds[NUM_LEDS];
void setup() {
// put your setup code here, to run once:
FastLED.addLeds<WS2812B, DATA_PIN, GRB>(leds, NUM_LEDS);
FastLED.setBrightness(5);
Serial.begin(115200);
pinMode(LED_BUILTIN_TX,INPUT);
pinMode(LED_BUILTIN_RX,INPUT);
}
void loop() {
// put your main code here, to run repeatedly:
char inByte = ' ';
StrNumbers = "";
Text = "";
Separrator = 0;
Cpu_Read = "";
Gpu_Read = "";
Ram_Read = "";
Received = 0;
pinMode(LED_BUILTIN_TX,INPUT);
while(Serial.available() > 0){ // only send data back if data has been sent
pinMode(LED_BUILTIN_TX,OUTPUT);
inByte = Serial.read(); // read the incoming data
if (inByte == ','){
Separrator += 1;
}
else if (Separrator == 0){
Cpu_Read += (char) inByte;
}
else if (Separrator == 1){
Gpu_Read += (char) inByte;
}
else if (Separrator == 2){
Ram_Read += (char) inByte;
Serial.print("Ram : ");
Serial.println(Ram_Read);
}
else{
Serial.println("Error");
}
/*
inByte = Serial.read(); // read the incoming data
if (isDigit(inByte)) { // tests if inByte is a digit
StrNumbers += (char) inByte;
Serial.println(inByte); // send the data back in a new line so that it is not all one long line
//Serial.println(numbers); // send the data back in a new line so that it is not all one long line
}
else if (inByte == ".")
{
abortLoop = 1;
}
else{
Text +=(char) inByte;
}
*/
Received = 1;
}
if (Received == 1){
Cpu = Cpu_Read.toInt();
Gpu = Gpu_Read.toInt();
Ram = Ram_Read.toInt();
UpdateMonitor(Cpu ,Gpu ,Ram);
}
Text.trim();
if (StrNumbers != ""){
numbers = StrNumbers.toInt();
Serial.println(numbers);
if (numbers > 100) numbers = 100;
UpdateMonitor(Cpu,numbers,Ram);
}
if(Text!= ""){
//Serial.println(Text); // send the data back in a new line so that it is not all one long line
}
if (Text == "ResourceMonitor"){
Serial.println("Yes");
}
else if (Text != ""){
Serial.println(Text);
numbers = Text.toInt();
if (numbers > 100) numbers = 100;
UpdateMonitor(Cpu, numbers, Ram);
}
}
void UpdateMonitor(int cpu,int gpu, int ram){
int Cpu_Usage = map(cpu, 0, 100, 0, 5);
int Gpu_Usage = map(gpu, 0, 100, 0, 5);
int Ram_Usage = map(ram, 0, 100, 0, 5);
FastLED.clear();
for(int led = 0; led < Ram_Usage; led++) {
leds[led] = CRGB::Blue;
}
for(int led = 0; led < Gpu_Usage; led++) {
leds[9 - led] = CRGB::Green;
}
for(int led = 0; led < Cpu_Usage; led++) {
leds[led+10] = CRGB::Red;
}
FastLED.show();
}

it is fixed now not sure what fixet it but it works atleast :)
thansk to all that have tried to helt

Inputting, splitting, and sorting in C

I am a python programmer. My girlfriend is taking a C class. This frustrates me, something so simple I can't find online nor I can figure out. Let's cut to the chase. I have a simple Python program that I need help trying to translate to C.
lst = input("Enter a list of numbers with a space in between each number\n")
newList = lst.split(" ")
#selection sort has been pre defined
x = newList.selectSort()
print(x)
Sorry this was done on my phone.
Her assignment isn't just this. It's adding multiple functions that work together. I just need to know how this works in order to pull the full program together.

First of all, you have to define the number of item in the list then you can input them.
Then, you have to store them in an array and do the sorting process manually.
I've done the sorting process without defining a function. If you want to use a function, just pass the array and return the sorted array.
#include <stdio.h>
int main()
{
int n, c, d, position, swap;
printf("Enter number of elements\n");
scanf("%d", &n);
int array[n];
printf("Enter %d integers\n", n);
for ( c = 0 ; c < n ; c++ )
scanf("%d", &array[c]);
for ( c = 0 ; c < ( n - 1 ) ; c++ )
{
position = c;
for ( d = c + 1 ; d < n ; d++ )
{
if ( array[position] > array[d] )
position = d;
}
if ( position != c )
{
swap = array[c];
array[c] = array[position];
array[position] = swap;
}
}
printf("Sorted list in ascending order:\n");
for ( c = 0 ; c < n ; c++ )
printf("%d\n", array[c]);
return 0;
}

#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
// Macro for sorting
#define sort(name, data_set, len, comparator, inverse) \
name##_sort(data_set, len, comparator, inverse)
#define SORT_DEFINE(name, data_type) \
\
/* Sort data set
#data_set data set to sort
#len length of data set
#comparator comparator to compare two elements, return positive value when first element is bigger
#inverse whether the result should be inversed
*/\
void name##_sort(data_type *data_set, int len, int (*comparator)(data_type, data_type), bool inverse) \
{ \
int i; \
int j; \
bool change = true; \
int ret; \
data_type tmp; \
\
for (i = 0; change && i < len - 1; i++) \
{ \
change = false; \
for (j = 0; j < len - 1 - i; j++) \
{ \
ret = comparator(data_set[j], data_set[j + 1]); \
if ((!inverse && ret > 0) || (inverse && ret < 0)) \
{ \
change = true; \
tmp = data_set[j]; \
data_set[j] = data_set[j + 1]; \
data_set[j + 1] = tmp; \
} \
} \
} \
}
/* Split string
#content origin string content
#delim delimiter for splitting
#psize pointer pointing at the variable to store token size
#return tokens after splitting
*/
const char **split(char *content, const char *delim, int *psize)
{
char *token;
const char **tokens;
int capacity;
int size = 0;
token = strtok(content, delim);
if (!token)
{
return NULL;
}
// Initialize tokens
tokens = malloc(sizeof(char *) * 64);
if (!tokens)
{
exit(-1);
}
capacity = 64;
tokens[size++] = token;
while ((token = strtok(NULL, delim)))
{
if (size >= capacity)
{
tokens = realloc(tokens, sizeof(char *) * capacity * 2);
if (!tokens)
{
exit(-1);
}
capacity *= 2;
}
tokens[size++] = token;
}
*psize = size;
return tokens;
}
// Define sort function for data_type = const char *
SORT_DEFINE(str, const char *);
// Define sort function for data_type = int
SORT_DEFINE(int, int)
int intcmp(int v1, int v2)
{
return v1 - v2;
}
int main(int argc, char *argv[])
{
char buff[128];
const char **tokens;
int size;
int i;
int *ints;
// Get input from stdin
fgets(buff, 128, stdin);
// Split string
tokens = split(buff, " \t\n", &size);
ints = malloc(sizeof(int) * size);
// Sort strings [min -> max]
sort(str, tokens, size, strcmp, false);
// Print strings and transfer them to integers
for (i = 0; i < size; i++)
{
printf("[%02d]: <%s>\n", i, tokens[i]);
ints[i] = atoi(tokens[i]);
}
// Sort integers [max -> min]
sort(int, ints, size, intcmp, true);
// Print integers
for (i = 0; i < size; i++)
{
printf("[%02d]: <%d>\n", i, ints[i]);
}
free(ints);
free(tokens);
return 0;
}
Use macro SORT_DEFINE(), sort(), and function split() to do your own job. The main() function is just a demo to show how to use them.

Triggering data acquisition in Arduino with Python

I would like to trigger data acquisition on my Arduino UNO with connected accelerometer (MPU 6050) by using Python.
The idea is that when the command is given in Python, the Arduino would start saving data on its SRAM and when a certain number of measurements would be saved, the data would be sent in a package back to Python.
This is my current Arduino code:
#include<Wire.h>
#define MPU6050_DLPF_94HZ MPU6050_DLPF_CFG_2
const int MPU_addr_1 = 0x68; // I2C address of the first MPU-6050
const int baudrate = 19200;
int16_t AcX1; // definition of variables
const int len = 200; // Buffer size
float analogDataArray[len];
int count = 0;
void setup() {
Wire.begin();
Wire.beginTransmission(MPU_addr_1);
Wire.write(0x6B); // PWR_MGMT_1 register
Wire.write(0); // set to zero (wakes up the MPU-6050)
Wire.endTransmission(true);
Serial.begin(baudrate);
}
void loop() {
Wire.beginTransmission(MPU_addr_1);
Wire.write(0x3B); // starting with register 0x3B (ACCEL_XOUT_H)
Wire.endTransmission(false);
Wire.requestFrom(MPU_addr_1, 8, true); // request a total of 14 registers
float AcX1 = Wire.read() << 8 | Wire.read(); // 0x3B (ACCEL_XOUT_H) & 0x3C (ACCEL_XOUT_L)
if (Serial.available())
{
if (Serial.read() == 'Y') {
analogDataArray[count] = AcX1;
count = count + 1;
if (count >= len) {
for (int i; i <= len; i = i + 1) {
Serial.println(analogDataArray[i] / 16384);
}
}
count = 0;
}
}
delay(5);
}
and this is my Python code:
import serial
arduinoData = serial.Serial('COM3', 19200)
com = input('Press "Y":' )
arduinoData.write(bytes(com, 'utf-8'))
vec = []
run = True
while run is True:
while (arduinoData.inWaiting() == 0):
pass
arduinoString = arduinoData.readline()
vec.append(float(arduinoString))
if len(vec) >= 100:
run = False
print(vec)
I've managed to get it working for 1 measurement but as soon as I defined an array inside Arduino to save multiple measurements, the code doesn't work. I'm sure that it is close to working, but I can't find the detail that is stopping me from that.
Thank you for any provided help.
Kind regards,
L

I got it working, the problem was in my Arduino code, as expected.
#include<Wire.h>
#define MPU6050_DLPF_94HZ MPU6050_DLPF_CFG_2
const int MPU_addr_1 = 0x68; // I2C address of the first MPU-6050
const int baudrate = 9600;
int16_t AcX1; // definition of variables
const int len = 200; // Buffer size
float analogDataArray[len];
int count = 0;
int ans;
void setup() {
Wire.begin();
Wire.beginTransmission(MPU_addr_1);
Wire.write(0x6B); // PWR_MGMT_1 register
Wire.write(0); // set to zero (wakes up the MPU-6050)
Wire.endTransmission(true);
Serial.begin(baudrate);
}
void loop() {
Wire.beginTransmission(MPU_addr_1);
Wire.write(0x3B); // starting with register 0x3B (ACCEL_XOUT_H)
Wire.endTransmission(false);
Wire.requestFrom(MPU_addr_1, 8, true); // request a total of 14 registers
float AcX1 = Wire.read() << 8 | Wire.read(); // 0x3B (ACCEL_XOUT_H) & 0x3C (ACCEL_XOUT_L)
if (Serial.available() && Serial.read() == 'Y') {
ans = 1;
}
if (ans == 1) {
analogDataArray[count] = AcX1;
count = count + 1;
if (count >= len) {
for (int i; i <= len; i = i + 1) {
Serial.println(analogDataArray[i] / 16384);
}
ans = 0;
}
}
delay(5);
}

Unpacking hex-encoded floats

I'm trying to translate the following Python code into C++:
import struct
import binascii
inputstring = ("0000003F" "0000803F" "AD10753F" "00000080")
num_vals = 4
for i in range(num_vals):
rawhex = inputstring[i*8:(i*8)+8]
# <f for little endian float
val = struct.unpack("<f", binascii.unhexlify(rawhex))[0]
print val
# Output:
# 0.5
# 1.0
# 0.957285702229
# -0.0
So it reads 32-bit worth of the hex-encoded string, turns it into a byte-array with the unhexlify method, and interprets it as a little-endian float value.
The following almost works, but the code is kind of crappy (and the last 00000080 parses incorrectly):
#include <sstream>
#include <iostream>
int main()
{
// The hex-encoded string, and number of values are loaded from a file.
// The num_vals might be wrong, so some basic error checking is needed.
std::string inputstring = "0000003F" "0000803F" "AD10753F" "00000080";
int num_vals = 4;
std::istringstream ss(inputstring);
for(unsigned int i = 0; i < num_vals; ++i)
{
char rawhex[8];
// The ifdef is wrong. It is not the way to detect endianness (it's
// always defined)
#ifdef BIG_ENDIAN
rawhex[6] = ss.get();
rawhex[7] = ss.get();
rawhex[4] = ss.get();
rawhex[5] = ss.get();
rawhex[2] = ss.get();
rawhex[3] = ss.get();
rawhex[0] = ss.get();
rawhex[1] = ss.get();
#else
rawhex[0] = ss.get();
rawhex[1] = ss.get();
rawhex[2] = ss.get();
rawhex[3] = ss.get();
rawhex[4] = ss.get();
rawhex[5] = ss.get();
rawhex[6] = ss.get();
rawhex[7] = ss.get();
#endif
if(ss.good())
{
std::stringstream convert;
convert << std::hex << rawhex;
int32_t val;
convert >> val;
std::cerr << (*(float*)(&val)) << "\n";
}
else
{
std::ostringstream os;
os << "Not enough values in LUT data. Found " << i;
os << ". Expected " << num_vals;
std::cerr << os.str() << std::endl;
throw std::exception();
}
}
}
(compiles on OS X 10.7/gcc-4.2.1, with a simple g++ blah.cpp)
Particularly, I'd like to get rid of the BIG_ENDIAN macro stuff, as I'm sure there is a nicer way to do this, as this post discusses.
Few other random details - I can't use Boost (too large a dependency for the project). The string will usually contain between 1536 (83*3) and 98304 float values (323*3), at most 786432 (643*3)
(edit2: added another value, 00000080 == -0.0)

The following is your updated code modified to remove the #ifdef BIG_ENDIAN block. It uses a read technique that should be host byte order independent. It does this by reading the hex bytes (which are little endian in your source string) into a big endian string format compatible with the iostream std::hex operator. Once in this format it should not matter what the host byte order is.
Additionally, it fixes a bug in that rawhex needs to be zero terminated to be inserted into convert without trailing garbage in some cases.
I do not have a big endian system to test on, so please verify on your platform. This was compiled and tested under Cygwin.
#include <sstream>
#include <iostream>
int main()
{
// The hex-encoded string, and number of values are loaded from a file.
// The num_vals might be wrong, so some basic error checking is needed.
std::string inputstring = "0000003F0000803FAD10753F00000080";
int num_vals = 4;
std::istringstream ss(inputstring);
size_t const k_DataSize = sizeof(float);
size_t const k_HexOctetLen = 2;
for (uint32_t i = 0; i < num_vals; ++i)
{
char rawhex[k_DataSize * k_HexOctetLen + 1];
// read little endian string into memory array
for (uint32_t j=k_DataSize; (j > 0) && ss.good(); --j)
{
ss.read(rawhex + ((j-1) * k_HexOctetLen), k_HexOctetLen);
}
// terminate the string (needed for safe conversion)
rawhex[k_DataSize * k_HexOctetLen] = 0;
if (ss.good())
{
std::stringstream convert;
convert << std::hex << rawhex;
uint32_t val;
convert >> val;
std::cerr << (*(float*)(&val)) << "\n";
}
else
{
std::ostringstream os;
os << "Not enough values in LUT data. Found " << i;
os << ". Expected " << num_vals;
std::cerr << os.str() << std::endl;
throw std::exception();
}
}
}

I think the whole istringstring business is an overkill. It's much easier to parse this yourself one digit at a time.
First, create a function to convert a hex digit into an integer:
signed char htod(char c)
{
c = tolower(c);
if(isdigit(c))
return c - '0';
if(c >= 'a' && c <= 'f')
return c - 'a' + 10;
return -1;
}
Then simply convert the string into an integer. The code below doesn't check for errors and assumes big endianness -- but you should be able to fill in the details.
unsigned long t = 0;
for(int i = 0; i < s.length(); ++i)
t |= (t << 4) & htod(s[i]);
Then your float is
float f = * (float *) &t;

This is what we ended up with, OpenColorIO/src/core/FileFormatIridasLook.cpp
(Amardeep's answer with the unsigned uint32_t fix would likely work also)
// convert hex ascii to int
// return true on success, false on failure
bool hexasciitoint(char& ival, char character)
{
if(character>=48 && character<=57) // [0-9]
{
ival = static_cast<char>(character-48);
return true;
}
else if(character>=65 && character<=70) // [A-F]
{
ival = static_cast<char>(10+character-65);
return true;
}
else if(character>=97 && character<=102) // [a-f]
{
ival = static_cast<char>(10+character-97);
return true;
}
ival = 0;
return false;
}
// convert array of 8 hex ascii to f32
// The input hexascii is required to be a little-endian representation
// as used in the iridas file format
// "AD10753F" -> 0.9572857022285461f on ALL architectures
bool hexasciitofloat(float& fval, const char * ascii)
{
// Convert all ASCII numbers to their numerical representations
char asciinums[8];
for(unsigned int i=0; i<8; ++i)
{
if(!hexasciitoint(asciinums[i], ascii[i]))
{
return false;
}
}
unsigned char * fvalbytes = reinterpret_cast<unsigned char *>(&fval);
#if OCIO_LITTLE_ENDIAN
// Since incoming values are little endian, and we're on little endian
// preserve the byte order
fvalbytes[0] = (unsigned char) (asciinums[1] | (asciinums[0] << 4));
fvalbytes[1] = (unsigned char) (asciinums[3] | (asciinums[2] << 4));
fvalbytes[2] = (unsigned char) (asciinums[5] | (asciinums[4] << 4));
fvalbytes[3] = (unsigned char) (asciinums[7] | (asciinums[6] << 4));
#else
// Since incoming values are little endian, and we're on big endian
// flip the byte order
fvalbytes[3] = (unsigned char) (asciinums[1] | (asciinums[0] << 4));
fvalbytes[2] = (unsigned char) (asciinums[3] | (asciinums[2] << 4));
fvalbytes[1] = (unsigned char) (asciinums[5] | (asciinums[4] << 4));
fvalbytes[0] = (unsigned char) (asciinums[7] | (asciinums[6] << 4));
#endif
return true;
}