error: 'ltoa' was not declared in this scope; did you mean 'utoa'?

[witsoft001]

the test code is

void setup() {
// put your setup code here, to run once:
long num=12345;
char s[20];
ltoa(num,s,10);
}

the above code , when compile ,report below information:

D:\arduino-1.8.19\portable\sketchbook\sketch_may28a\sketch_may28a.ino: In function 'void setup()':
sketch_may28a:7:1: error: 'ltoa' was not declared in this scope; did you mean 'utoa'?
7 | ltoa(num,s,10);
| ^~~~
| utoa
exit status 1
'ltoa' was not declared in this scope; did you mean 'utoa'?

the select board is GD32F3x0 Generic series, GD32F330C4, change to another type of GD32 is also this error. When I change the board to STM32 for arduino platform , the code is compile ok .

What's wrong with this problem?

thanks who can help me resolve this error.

[maxgerhardt]

Did you try to

#include <stdlib.h>

first?

The "Arduino way" would be to do

long num = 12345;
String asString = String(num);
const char* asCString = asString.c_str();