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ETLCPP / etl

Embedded Template Library
https://www.etlcpp.com
MIT License
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etl::string_ext without initializing string possible? #796

Closed basprins closed 10 months ago

basprins commented 10 months ago

Hi, Is there any way I can support the following?

I have a uint8_t * buffer which is filled with raw bytes after reading from flash (ascii based). This buffer contains characters I need to replace, so I want to use this buffer in a string. I through the et::string_ext would fit my needs. Lets say I have a buffer of 512, which I can guarantee is only filled with 256 characters. Then I want to make an etl string_ext for the buffer of 512 bytes (knowing that at a maximum only half of the buffer contains data). Then I can "freely" start seaching and replacing characters to my need.

But every constructor of etl_string_ext also initializes (or assigns) the string, resulting in overwriting the first byte in the string with a 0x0 byte. I explicitly don't want that, I just want to get all the features of etl::string_ext, without tampering with the data. I want etl to only set the size of the string based on the 0x0 terminated string, but leave all preexisting characters alone.

Is this possible? And if so, could you give me a hint, because I'm looking in the wrong places it seems.

jwellbelove commented 10 months ago

There isn't a way at the moment. I will have to add a flag to the constructor to disable null termination of the buffer. I can send you an interim patch if you like?

basprins commented 10 months ago

Oh you are fast! Yes, that would be fantastic. I sorted it locally by saving and restoring the first byte and uninitialized resize. But a fix in ETL would be great of course.

jwellbelove commented 10 months ago

Actually, there is a way, I just forgot about it. You use this constructor...

string_ext(const char* text, char* buffer, size_type buffer_size) The constructor will recognise that the address of text is the same as buffer and just set the size of the string to the length of text.

basprins commented 10 months ago

I will be damned.

But every constructor of etl_string_ext also initializes (or assigns) the string

I would've sworn I tried them all. But I confirm, problem solved! Thank you sir!

jwellbelove commented 10 months ago

But every constructor of etl_string_ext also initializes (or assigns) the string

If the address of text is different from buffer, then it will.

basprins commented 10 months ago

Yeah had a quick look, silly that I missed that.