Transform char array into String - string

Question

I have a function that returns a char array and I want that turned into a String so I can better process it (compare to other stored data). I am using this simple for that should work, but it doesn't for some reason (bufferPos is the length of the array, buffer is the array and item is an empty String):
for(int k=0; k<bufferPos; k++){
item += buffer[k];
}
The buffer has the right values and so does bufferPos, but when I try to convert, for example 544900010837154, it only holds 54. If I add Serial.prints to the for like this:
for(int k=0; k<bufferPos; k++){
Serial.print(buffer[k]);
Serial.print("\t");
Serial.println(item);
item += buffer[k];
}
the output is this:
5
4 5
4 54
9 54
0 54
0 54
0 54
1 54
0 54
8 54
3 54
7 54
1 54
What am I missing? It feels like such a simple task and I fail to see the solution...

Answer 1

If you have the char array null terminated, you can assign the char array to the string:
char[] chArray = "some characters";
String String(chArray);
As for your loop code, it looks right, but I will try on my controller to see if I get the same problem.

Answer 2

Three years later, I ran into the same problem. Here's my solution, everybody feel free to cut-n-paste. The simplest things keep us up all night! Running on an ATMega, and Adafruit Feather M0:
void setup() {
// turn on Serial so we can see...
Serial.begin(9600);
// the culprit:
uint8_t my_str[6]; // an array big enough for a 5 character string
// give it something so we can see what it's doing
my_str[0] = 'H';
my_str[1] = 'e';
my_str[2] = 'l';
my_str[3] = 'l';
my_str[4] = 'o';
my_str[5] = 0; // be sure to set the null terminator!!!
// can we see it?
Serial.println((char*)my_str);
// can we do logical operations with it as-is?
Serial.println((char*)my_str == 'Hello');
// okay, it can't; wrong data type (and no terminator!), so let's do this:
String str((char*)my_str);
// can we see it now?
Serial.println(str);
// make comparisons
Serial.println(str == 'Hello');
// one more time just because
Serial.println(str == "Hello");
// one last thing...!
Serial.println(sizeof(str));
}
void loop() {
// nothing
}
And we get:
Hello // as expected
0 // no surprise; wrong data type and no terminator in comparison value
Hello // also, as expected
1 // YAY!
1 // YAY!
6 // as expected
Hope this helps someone!

Answer 3

Visit https://www.arduino.cc/en/Reference/StringConstructor to solve the problem easily.
This worked for me:
char yyy[6];
String xxx;
yyy[0]='h';
yyy[1]='e';
yyy[2]='l';
yyy[3]='l';
yyy[4]='o';
yyy[5]='\0';
xxx=String(yyy);

Answer 4

May you should try creating a temp string object and then add to existing item string.
Something like this.
for(int k=0; k<bufferPos; k++){
item += String(buffer[k]);
}

Answer 5

I have search it again and search this question in baidu.
Then I find 2 ways:
1,
char ch[]={'a','b','c','d','e','f','g','\0'};
string s=ch;
cout<<s;
Be aware to that '\0' is necessary for char array ch.
2,
#include<iostream>
#include<string>
#include<strstream>
using namespace std;
int main()
{
char ch[]={'a','b','g','e','d','\0'};
strstream s;
s<<ch;
string str1;
s>>str1;
cout<<str1<<endl;
return 0;
}
In this way, you also need to add the '\0' at the end of char array.
Also, strstream.h file will be abandoned and be replaced by stringstream