#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <limits.h>
FILE *fp;
void putNumsInFile(FILE *fp1){
    int ch;
    while ( (ch=fgetc(stdin)) != 'z' ) {
        int num1,num2;
        scanf("%d",&num1);
        scanf("%d",&num2);
        fprintf(fp1,"%d %d\n",num1,num2);
        }
    }
 int * minMax (FILE *fp){
        int min = INT_MIN;
        int max = INT_MAX;
        int readNum = 0;
        int c = 0;
        int sum = 0;
        c= getc(fp);
        while (c != EOF)
        {
            c= getc(fp);
            fscanf (fp, "%d", &readNum);
            if(readNum < max){
                min = readNum;
                }
            if(min < readNum){
                max = readNum;
                }
        }
        int arr[2];
        arr[0] = min;
        arr[1] = max;
        return  arr;
    }
int main()
{
    char menu;
    char fileName[200];
        do{
            printf("\n");
            printf("1. Create a file\n");
            printf("2. Fill with numbers\n");
            printf("3. Difference between smallest end largest\n");
            printf("4. Quit\n");
            menu = getche();
            printf("\n");
            switch(menu){
                case '1': menu =' 1';break;
                case '2': {
                    fp = fopen(fileName, "r+");
                    putNumsInFile(fp);
                    fclose(fp);
                    };break;
                case '3': {
                    fp = fopen(fileName, "r+");
                    int *p;
                    p = minMax(fp);
                    printf("min: %d", p);
                    printf("max: %d", p + 1);
                    fclose(fp);
                    };break;
                case '4': printf("\n\nGoodbye");break;
                default: printf("\n\nPlease enter number between 1-4\n");
            }
            if(menu == '1'){
                printf("\nEnter file name:");
                scanf("%s",fileName);
                strcat(fileName,".txt");
                fp = fopen(fileName, "w+");
                fclose(fp);
                }

        }while(menu!= '4');
        return 0;
}