How do I convert a char to String?

I am converting data from a keypad. How do I convert a char to a String easily? Also, is there any way to stop an Arduino until it receives input from a keypad?

What kind of (s/S)tring?

"string" char Str1[15]; char Str2[8] = {'a', 'r', 'd', 'u', 'i', 'n', 'o'}; char Str3[8] = {'a', 'r', 'd', 'u', 'i', 'n', 'o', '\0'}; char Str4[ ] = "arduino"; char Str5[8] = "arduino"; char Str6[15] = "arduino";

OR

String object

Also, is there any way to stop an Arduino until it receives input from a keypad?

Stop the Arduino how, an example would be helpful, but first, we need to see your code.

A char is one character. A String is a collection of characters. Making a collection of one hardly seems useful. Looking at the String documentation does.

A String is a collection of characters.

So you saying a String can't be a single character?

So you saying a String can't be a single character?

Having reading comprehension problems again?

PaulS:

So you saying a String can't be a single character?

Having reading comprehension problems again?

No, just pointing out you seem to be a bit foggy on the subject. 8)

No, just pointing out you seem to be a bit foggy on the subject.

You're the one whose deliberately being stupid. There is no reason to wrap one char in a String.

You are wanting to program an MCU with no OS like you would a desktop PC, in top-down style.

Arduino C++ Strings fragment the heap on a machine that has 2048 bytes for heap and stack.

So you saying a String can’t be a single character?

A 1 char String has extra bytes in RAM that you may or may not know are there.
With char array strings you allocate ALL the space the string will use + 1 byte for terminating zero once.
#include <string.h>

char buffer[ 32 ]; // save up to 31 chars, initialized all 0
buffer[ 0 ] = ‘A’; // now buffer is a string, “A”
strcpy( buffer, “Hello World” );
Serial.println( buffer );

You’re better off learning and using C char array ‘strings’. They stay put and don’t do anything you didn’t code, like making a copy + 1 char then deleting the old copy just because you coded myword += “X”.

There are very good C Strings Tutorials on the web, just Google those words.

Also Arduino is made to do real-time code. You can task with ease, there’s no OS in the way!

Also, is there any way to stop an Arduino until it receives input from a keypad?

How about the Arduino is blinking 1 or more leds, playing a tune and maybe displaying time on an LCD while checking for input on a keypad 100 times a second? Because it can.

With char array strings you allocate ALL the space the string will use + 1 byte for terminating zero once.

Is the specific amount of memory space always allocated? Seems like I've seen code like below, which would indicate that c-strings also uses dynamic memory allocation.

char  buffer[  ];

In your code example below, looks like ~96% of your memory space is needlessly wasted.

char  buffer[ 32 ]; // save up to 31 chars, initialized all 0
buffer[ 0 ] = 'A'; // now buffer is a string, "A"
strcpy( buffer, "Hello World" ); 
Serial.println( buffer );

CDCosma: I mean the Object String. I want to do a sort of prompt. For example, it will ask the user to enter a first value, then a second value.

Using what?

Also, is there any way to stop an Arduino until it receives input from a keypad?

Loop until it receives input from the keypad?

I want to do a sort of prompt.

Why do you need a String ? How about ? Serial.print("Enter first number");

zoomkat: Is the specific amount of memory space always allocated? Seems like I've seen code like below, which would indicate that c-strings also uses dynamic memory allocation.

char  buffer[  ];

In your code example below, looks like ~96% of your memory space is needlessly wasted.

char  buffer[ 32 ]; // save up to 31 chars, initialized all 0
buffer[ 0 ] = 'A'; // now buffer is a string, "A"
strcpy( buffer, "Hello World" ); 
Serial.println( buffer );

With that first declaration, any attempt to put a char into buffer will not compile. The error is "storage size of 'buffer' isn't known".

In what way is any of that buffer wasted? Sure, it's wasted if you declare it with a size larger than the largest (string + 1), but that can hardly be called a wastage due to the compiler's allocation of memory. That's like blaming a car for wasting the ability to go 100 MPH just because you are only doing 20.

That was an example of setting up a buffer and some code that uses it, not a best fit.

The better prompt would be

Serial.print(F("Enter first number"));

That keeps the constant text in flash and not use RAM.