Questions tagged [c-string]
A "C string" is an array of characters that ends with a 0 (null character) byte. The array, not any pointer, is the string.
28 questions
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Parse char* mac-string to uint8_t array
I have to handle a String coming in over UART containing a bunch of information, part of it is a MAC-address that I get by using String.substring(a, b) returning a 12-char String representing a mac-...
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When Writing Library, return String or return char *
I am trying to write my own Arduino library and I would like to make it useful not just for ESP32/ESP8266 boards but also with Arduino boards.
I have created my header file like this
test.cpp
#...
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String() vs char for simple flow control
I am newbie in Arduino and writing a program where I want to control the flow by using Serial monitor input (PI controller).
I've read that using String() although easier it is slower than using char. ...
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String operations printing random character on Serial Monitor
I want to extract the file name MyFile.txt out of a path which is stored in a string "C:\\MyDirectory\\MyFile.txt";
I found a simple c code which does the job.
string filename = "C:\\...
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Using String instead of C string, yet another attempt to touch a loaded issue
I've been reading a lot over the years why we should not use the notorious String class and how heap fragmentation is bad practice and not professional and we should never use it in our programs or we'...
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Reading bits from a const char pointer
I'm getting a bit tripped up on const char pointers lately.
I'm getting a message from a server that comes through as either a c style string, a standard library string, or a WString:
I'm sending down ...
- 357
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Arduino - Function -> return Cstr instead of string
I have following function for my Arduino:
String readLine() {
String received = "";
char ch;
while (myFile.available()) {
ch = myFile.read();
if (ch == '\n' or ch == '\r') {
...
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Any explanation for this behavior?
For the below code snippet
const char* fr_fbdb(char tag[30]) // fn for retrieving data
{
char full_path[120];
const char *_dt ;
strcpy(full_path , base_path);
strcat(full_path , tag);
...
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Reading a string from Firebase and storing it as a CString
I have a mobile app (done using MIT App Inventor) storing some values to a Firebase database. App inventor stores all the values as strings (i.e. with quotes, and strings have quotes enclosed within ...
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strcmp doesn't seem to work
I'm trying to compare a char array that I'm assembling to a string and I'm having trouble comparing the strings.
I'm getting the data for the char array as a set of bytes and I'm compiling it into a ...
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snprintf doesn't display float values
I don't understand why the formatted string is displaying ?? instead of float values.
My code:
#include <Arduino.h>
#include <Wire.h>
#include "SparkFunCCS811.h"
#include <...
- 183
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Read Comma Separated String
I have a string that looks like this "10.00,20.00,-50.00," in which these are angle values and they have 2 decimals and can be negative. I want to separate them into 3 separate floats. Here ...
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Conversion from string to char array
I know this is Arduino Forum but I think this question is related to programming, I am using ESP8266 for the project. I need to convert the string incoming on the serial through UART lines and ...
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declaration of 'varDay' as array of references error
I am trying to write a function to store the date and time data from an RTC module. I have used char arrays to implement the function. I get "declaration of 'varDay' as array of references" ...
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Does toCharArray prevent a String being created on the heap?
I know it's bad to use Strings due to the memory problems that can occur.
I've tried to remove all instances of strings from my code.
But I'm not sure about this line:
http.getString().toCharArray(...
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