How to create a simple GTK shows reading value sensor DS18B20 rasberry pi

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C

Raspberry-Pi

hello guys, i am c programming user. i have a project using raspberry Pi. i have a temperature sensor ds18b20 and its code, i able show its reading value in uxterm or Terminal. i recently make a simple gtk (gui) that do not have any button or any toolbar. i only able make a label that does not connect to the sensor reading value. how do i combine these code in order to make a gtk (gui) that able display the temperature sensor reading value and able update its reading all the time in any second when temperature change? the project is only want C programming not other language. the below code are

/*dsb18b20 sensor c-language*/

#include <wiringPi.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <stdlib.h>
#include <stdio.h>

#define		BUFSIZE		128

typedef unsigned char uchar;
typedef unsigned int  uint;

float tempRead(void)
{
	float temp;
	int i, j;
    int fd;
	int ret;

	char buf[BUFSIZE];
	char tempBuf[5];
	
	fd = open("/sys/bus/w1/devices/28-0314979400b5/w1_slave", O_RDONLY);

	if(-1 == fd){
		perror("open device file error");
		return 1;
	}

	while(1){
		ret = read(fd, buf, BUFSIZE);
		if(0 == ret){
			break;	
		}
		if(-1 == ret){
			if(errno == EINTR){
				continue;	
			}
			perror("read()");
			close(fd);
			return 1;
		}
	}

	for(i=0;i<sizeof(buf);i++){
		if(buf[i] == 't'){
			for(j=0;j<sizeof(tempBuf);j++){
				tempBuf[j] = buf[i+2+j]; 	
			}
		}	
	}

	temp = (float)atoi(tempBuf) / 1000;

	close(fd);

	return temp;
}

int main(void)
{
	if(wiringPiSetup() == -1){
		printf("setup wiringPi failed !");
		return 1; 
	}
    float temp;
    while(1){
		temp = tempRead();
		printf("Current temperature : %0.3f\n", temp);
    }
    return 0;

}

/*simple gtk c-language*/


#include <gtk/gtk.h>

void main(int argc, char *argv[])
{
   gtk_init (&argc, &argv);
   GtkWidget *win = gtk_window_new (GTK_WINDOW_TOPLEVEL);

   gtk_window_set_default_size(GTK_WINDOW(win), 250, 150);

   GtkWidget *lbl = gtk_label_new ("100 C");
   gtk_container_add (GTK_CONTAINER (win), lbl);

   gtk_widget_show_all (win);

   gtk_main();

}

i am trying to replaced label "100 C" with live sensor reading. my gtk able shows reading value of sensors. can someone help me?

What I have tried:

i still starter learning c-programming, current i had no idea how to combine these 2 code.