OrangePi fan control via terminals GPIO

#include <wiringPi.h>
#include <stdio.h>
#include <unistd.h>
#define N 2
int main (void) {
    wiringPiSetup();
    pinMode(1,OUTPUT);
    int temp;
    char arr[N];
    FILE *file;
    while(1) {
        file = fopen("/sys/class/thermal/thermal_zone0/temp" , "r");
        fgets(arr,4,file);
        fclose(file);
        temp=(arr[0]-'0')*10+arr[1]-'0';
        printf("%i\n", temp);
        if(temp>55)
            digitalWrite(1,HIGH);
        else
            digitalWrite(1,LOW);
        delay(10000);
    }
    return 0;
}