Arduino Sring to const char
To convert an Arduino String to a const char in C++, follow these steps:
Declare a String variable: Start by declaring a String variable and assigning it the desired value.
Get the length of the String: Use the
length()
function to determine the length of the String. This will be useful when creating thechar
array later.Create a char array: Declare a
char
array with a size one greater than the length of the String. This extra space is needed to accommodate the null terminator character '\0'.Copy the String to the char array: Use the
toCharArray()
function to copy the contents of the String to the char array. The function takes two arguments: the name of the char array and its size.Add the null terminator character: Manually add the null terminator character '\0' at the end of the char array to indicate the end of the string.
Declare a const char pointer: Finally, declare a const char pointer and assign it the address of the first element of the char array. This pointer can now be used as a const char representation of the original String.
Here is an example:
String myString = "Hello, World!";
int length = myString.length();
char charArray[length + 1];
myString.toCharArray(charArray, length + 1);
charArray[length] = '\0';
const char* myConstChar = charArray;
Note: As always, it is important to manage memory properly. Ensure that the char array remains in scope and is not accessed after it goes out of scope to prevent undefined behavior.