c - fgets and dealing with CTRL+D input -


i grabbing standard input user , if user presses ctrl+d, want display error , terminate program. think perhaps issue may related being stuck in while loop;

int readinput(){    char buff[10];    int count = 0;    int counter;    printf("enter random number: ");    fgets(buff, 10, stdin);    if ((int) strtol(buff, null, 10) == 0){       printf("error reading number. \n");       return 0;   //this hit if user presses ctrl+d @ input.    }    counter = atol(buff);    while (count < counter){        printf("enter label: ");       fgets(buff, 10, stdin);       if ((int) strtol(buff, null, 10) == 0){          printf("error reading label");          return 0;  //this not hit if user presses ctrl+d @ input, why?          //i've tried assigning variable 0, breaking out of loop using break; , returning variable @ end of function not work.        //the rest of while loop continues if user hit ctrl+d       printf("enter value: " );       fgets(buff, 10, stdin);       //..rest of while loop gets other inputs above       count++;    }  //termination happens in main, if readinput returns 0 call return exit_failure;

i don't understand why @ first input if user presses ctrl+d, program responds accordingly second time ignores it.

on linux, ctrl + d generates eof, need check return value of fgets() every time. when eof encountered, fgets() returns null pointer

if (fgets(buff, 10, stdin) == null)     print_error();

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