String::clear() does not work as expected

[anp59]

Description:

Hi guys,
I noticed that the function String::clear() does not behave as expected. According to the name, it should clear the content of a string object, i.e. after this operation an empty String is returned. This works for all string methods except String::c_str(). Here, the content is retained.
Internally, the clear method only sets the length of the string to 0. For c_str(), however, the first character in the internal memory buf would also have to be set to 0 ('\0').

Sketch:

#include <Arduino.h>

void setup() {
    String s = "abc";
    Serial.print("print(s):         ->");Serial.println(s);
    Serial.print("print(s.c_str()): ->");Serial.println(s.c_str());
    s.clear();
    Serial.println("After s.clear():");
    Serial.print("print(s):         ->"); Serial.println(s);
    Serial.print("print(s.c_str()): ->"); Serial.println(s.c_str());
}

void loop() {
}

Output:

print(s):         ->abc
print(s.c_str()): ->abc
After s.clear():
print(s):         ->
print(s.c_str()): ->abc

[me-no-dev]

done :)