CS 121 Lab 4 Help sheet

lab4help.c

/********************************************
Hello Everyone, This is going to be a 
(hopefully) helpful sheet of notes for lab 4.
********************************************/

/* Open A File for reading, and check to make sure it exists */
FILE *some_file = NULL;
some_file = fopen("my_file_name.txt", "r");
if (some_file == NULL) {
    printf("This file does not exist!!\n");
    exit(1); //Cause program to die (you can do something else here too_
}
//File is now open.


/* Read diferent things from an already opened file */
int num_read = 0;
int my_number = 0;
double my_double = 0;
char my_letter = 0;

//fscanf returns the number of items it reads
//this might be useful to check!
num_read = fscanf(my_file, "%d%lf", &my_number, &my_double);

if (num_read != 2) {
    printf("Error: couldnt read correctly from file!\n");
    exit(1);
}

num_read = fscanf(my_file, "%c", &my_letter);
if (num_read != 1) {
    printf("Error: couldnt read a char from the file!\n");
    exit(1);
}

/****************************
*    Switch Statements!     *
****************************/

switch (anumber) {
    case 1:
        printf("Its a one!\n");
        break;
    case 2:
        printf("Its two ones! (or a two)\n");
        break;
    default:
        printf("everything else is boring...\n");
        break;
}