task

#include <stdio.h>
#include <math.h>
/*FILE*;
fopen(const char *, ...);
fclose(FILE*);
fscanf(FILE*, const char *, ...);
fprintf(FILE*, const char *, ...);
feof(FILE*);*/
double myabs(double n);
int number (const char *, int *,double);
double myabs(double n)
{
    return n>0?n:-n;
}
int number (const char *name, int *res,double x)
{
    FILE *fp;
    double y,max;
    int n=1,num=1;
    if (!(fp=fopen(name,"r"))) return -1;
    fscanf(fp,"%lf",&x);
    max=x;
    while (fscanf(fp,"%lf",&y)==1)
    {
        if (y>x)
        {
            max=y;
            num=n++;
        }
        n++;
        x=y;
    }
    if (!feof(fp))
    {
        fclose(fp);
        return -2;
    }
    fclose(fp);
    *res=max;
    return num;
}
int main(void)
{
    const char *fname="a.txt";
    double x;
    int ret,answer;
    ret=number(fname,&answer,x);
    if (ret<0)
    {
        switch (ret)
        {
            case -1:
            printf("Cannot open %s\n",fname);
            break;
            case -2:
            printf("Cannot read %s\n",fname);
            break;
            default:
            printf("Error %d in file %s",ret,fname);
        }
        return 1;
    }else{
    printf("Number=%d, position=%d\n",ret,answer);
    return 0;
    }
}