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I am using Arduino and receiving a string from serial. I have converted that string into a character array. But I need to convert first 4 or 5 elements of that array back to string. Is there any way to do that?

I tried the following but it doesn't work:

String str= String('a[0]');
Garf365
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Ismail Khawaja
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3 Answers3

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char* data = ...;
int size = 4;
std::string str(data, size);

It's elegant with constructor of std::string.

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What you want is the substr method of std::string.

You can convetr the char[] to an std::string, and then use substr to get the sub-string you want.

std::string str("The quick brown fox jumps over the lazy dog");
std::cout << str.substr(0, 9);

Output would be:

The quick

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Ivan Rubinson
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  • thank you for your quick response ivan. what im trying to do here is to get a string from serial. if the string starts with COMSTEP, go into the function in which i analyze the rest of the string and tokenize it. string comprise of characters seperated by spaces. do i have to convert the string to char or is there any other way to do that? P.S: im a noob at arduino. so any help is appreciated – Ismail Khawaja Aug 16 '16 at 12:04
  • If you already have a string, there's no need to convert it. Just substring the string you have. – Ivan Rubinson Aug 16 '16 at 12:06
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char arr[m];
std::string str="";
for(int i = 0; i < n; i++) {
    str += arr[i];
}

I have assumed that you would like to convert first n element of char aar into string.

Or 

char* inp = ..;
int size = 4; // int size = 5;
std::string str(inp, size);
Shravan40
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