identifier "strnlen" is undefined on VSCode PlatformIO

[jiyi27]

I have install this library, and compiled my project successfully, but I am wondering why have this issue in PubSubClient.cpp? [{ "resource": "/C:/qwer/.pio/libdeps/esp12e/PubSubClient/src/PubSubClient.cpp", "message": "identifier "strnlen" is undefined", "source": "C/C++", "startLineNumber": 235, }]

[IronBamBam1990]

#include <string.h>

or paste this

size_t strnlen (const char *, size_t);

[JamesDelfini]

Mine works by Configuring the IntelliSense for C/C++ at Compiler Arguments and adding the compiler flag below.

I add the same problem and I found out that using -std=gnu++11 compiler flag solves it.