Convert std::string to String

maxgerhardt · May 20, 2022, 1:27pm

You can get the std::string’s C-string (const char* via calling c_str() on the object, then feed that in the constructor of String. This will cause double memory usage, String will copy it into a newly allocated buffer. (Henc why equalization is kinda important).

std:string cpp_str = "Hello";
String ard_str = String(cpp_str.c_str());

github.com

espressif/arduino-esp32/blob/master/cores/esp32/WString.h#L52-L67


      
                  // constructors
                  // creates a copy of the initial value.
                  // if the initial value is null or invalid, or if memory allocation
                  // fails, the string will be marked as invalid (i.e. "if (s)" will
                  // be false).
                  String(const char *cstr = "");
                  String(const char *cstr, unsigned int length);
          #ifdef __GXX_EXPERIMENTAL_CXX0X__
                  String(const uint8_t *cstr, unsigned int length) : String((const char*)cstr, length) {}
          #endif
                  String(const String &str);
                  String(const __FlashStringHelper *str);
          #ifdef __GXX_EXPERIMENTAL_CXX0X__
                  String(String &&rval);
                  String(StringSumHelper &&rval);
          #endif