Some code error can anyone help

#include <SPI.h>
#include <DMD.h>
#include <TimerOne.h>
#include "SystemFont5x7.h"
#include "Arial_black_16.h"
#define ROW 1
#define COLUMN 1
#define FONT Arial_Black_16
char input;
int a = 0, b = 0;
int flag = 0;
char cstr1[100];
DMD led_module(ROW, COLUMN);
String data="";
void scan_module()
{
led_module.scanDisplayBySPI();
}
void setup()
{
Serial.begin(115200);
Timer1.initialize(2000);
Timer1.attachInterrupt(scan_module);
led_module.clearScreen( true );
}
void loop()
{
if (Serial.available())
{
data=Serial.readString();
}
Serial.println(data);
(String("Score:")+String(data)).toCharArray(cstr1, 100);
led_module.selectFont(FONT);
led_module.drawMarquee(cstr1,100, (32 * ROW), 0);
long start = millis();
long timming = start;
boolean flag = false;
while (!flag)
{
if ((timming + 30) < millis())
{
flag = led_module.stepMarquee(-1, 0);
timming = millis();
}
}
}

Can we expect a question?
Code tags?
Error messages?

Hello there, Would you please specify the problem? Is it not getting compiled or not showing the expected result after uploading?

one error i saw with warnings set, is a comparison between a signed, "timming" and unsigned, millis() value

why does processing continue regard of whether serial input is available and read? should loop() return if serial is NOT available

not sure what this does or is intended to do. why is there a "+"?

shouldn't this be done in setup()?

    boolean         flag = false;
    while (!flag)
    {
        if ((timming + 30) < millis())
        {
            flag = led_module.stepMarquee(-1, 0);
            timming = millis();
        }
    }

this seems unnecessary shouldn't the marquee be constantly scrolling?

should the code be

void loop()
{
    if (Serial.available())
    {
        data=Serial.readString();
        Serial.println(data);

        (String("Score:")+String(data)).toCharArray(cstr1, 100);
        led_module.drawMarquee(cstr1,100, (32 * ROW), 0);
    }

    static unsigned long timming;

    if ((millis() - timming > 30))  {
        timming = millis();
        if (true == led_module.stepMarquee(-1, 0))
            led_module.drawMarquee(cstr1,100, (32 * ROW), 0);
    }
}