hw7-no-bag

//string.h is used for puts, while stdlib is used for malloc/realloc
//and ctype for isalnum and ispunct.
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <ctype.h>

//function that checks if malloc and realloc succeed.
void memCheck(char *str);

//main function.
int main(int argc, char *argv[])
{
    //str is the string used to hold the contents of the file.
    //ch temporarily holds the char being read from the file before it gets but in str.
    //fp is the pointer to input stream from the file named in filename.
    //x, y, z are counters. x for chars, y for words, and z for lines.
    char *str, ch;
    FILE *fp;
    int x = 0, y = 0, z = 0;

    //tests for valid arguments.
    if (argc-2)
    {
        puts("Invalid arguments. Usage: ./daniel_sawyer_hw07 NameOfFile.txt\nTry again.\n");
        return 0;
    }

    //it opens the file stream and checks to make sure the file is in the correct location.
    fp = fopen(argv[1], "r");
    if (fp == NULL)
    {
        puts("Invalid file. Usage: ./daniel_sawyer_hw07 NameOfFile.txt\nMake sure file is in same direcotry as binary and try again.\n");
        return 0;
    }

    //allocates memory for the str pointer effectively turning it into a char array size 1 and tests if its successful.
    str = malloc(sizeof(char));
    memCheck(str);

    //loop that reads every char in the input file and counts all the chars, words, and lines that are in the file.
    while ((ch = getc(fp)) != EOF)
    {
        //counts words and lines. if previous character was alpha/num or punctuation, it increments the word variable y.
        //also counts lines (z) everytime the \n char is detected.
        switch(ch)
        {
            case ' '  : if ( isalnum(str[x-1]) || ispunct(str[x-1]) ) ++y; break;
            case '\n' : if ( isalnum(str[x-1]) || ispunct(str[x-1]) ) ++y; ++z; break;
        }

        //reallocates memory for the string to x+1 chars and then checks if allocation was successful.
        str = realloc(str, (x+1) * sizeof(char));
        memCheck(str);

        //puts the char in the string then increments x.
        str[x++] = ch;
    }

    //closes file stream since it is no longer needed.
    fclose(fp);

    //increments z to the correct number of lines.
    ++z;
    //checks to make sure the last char was alpha/num or punctuation.
    //if it is, it increments y (words) to the correct amount.
    if ( isalnum(str[x-1]) || ispunct(str[x-1]) )
        ++y;

    //prints the number of chars, words, and lines in the input file.
    printf("\nNumber of Characters: %d\n", x);
    printf("\nNumber of Words: %d\n", y);
    printf("\nNumber of Lines: %d\n", z);

    //ends program.
    return 0;
}

//memory check function. if mem runs out, kills program.
void memCheck(char *str)
{
    if (str == NULL)
    {
        puts("Memory allocation failed. Please try again.\n");
        exit(EXIT_FAILURE);
    }
}