Creating a Function in my C Program? - Getting Statistics for 2 Text Files

Question

I was wondering how would I be able to narrow this down so that I don't have to have so many pieces of code repeated? I'm not so sure on how to create functions and call upon them in the main program.

#define _CRT_SECURE_NO_WARNINGS

#include <stdio.h>
#include <string.h>
#include <stdlib.h>

void main() {
FILE *openFile;
char fileName1[1500] = "", fileName2[1500] = "";
char character;
int lineCount, wordCount, charCount;

printf("Enter the first filename: ");
gets(fileName1);

openFile = fopen(fileName1, "r");

lineCount = 0;
wordCount = 0;
charCount = 0;

if (openFile)   {

    while ((character = getc(openFile)) != EOF)
    {

        if (character != ' ' && character != '\n')
        {
            ++charCount;
        }

        if (character == ' ' || character == '\n')
        {
            ++wordCount;
        }
        if (character == '\n')
        {
            ++lineCount;
        }
    }
    if (charCount > 0)
    {
        ++lineCount;
        ++wordCount;
    }
}

else
{
    printf("Failed to open the file\n");
}

    printf("The number of lines : %d \n", lineCount);
    printf("The number of words: %d \n", wordCount);
    printf("The number of characters : %d \n", charCount);

fclose(openFile);

printf("Enter the second filename: ");
    gets(fileName2);

    openFile = fopen(fileName2, "r");

    lineCount = 0;
    wordCount = 0;
    charCount = 0;

    if (openFile)   {

        while ((character = getc(openFile)) != EOF)
        {

            if (character != ' ' && character != '\n')
            {
                ++charCount;
            }

            if (character == ' ' || character == '\n')
            {
                ++wordCount;
            }
            if (character == '\n')
            {
                ++lineCount;
            }
        }
        if (charCount > 0)
        {
            ++lineCount;
            ++wordCount;
        }
    }

    else
    {
        printf("Failed to open the file\n");
    }

    printf("The number of lines : %d \n", lineCount);
    printf("The number of words: %d \n", wordCount);
    printf("The number of characters : %d \n", charCount);

    fclose(openFile);

getchar();
}

Answer 1

1) Loops exist for a reason! Generally when you have to do the same thing over and over again, loops are what you really need. Just use a for loop which runs for 2 times.

Note: void main() is not a valid signature for main() in c, instead use int main(void) as you are sending no arguments into main()

Using for loop, your main() would look like:

char fileName[1500] = ""; //just a single variable is enough to store file name
//other declarations

for(int i = 1; i <= 2; i++) //loop to make it happen 2 times
{
    printf("Enter the %d filename: ", i);
    gets(fileName);

    openFile = fopen(fileName, "r");

    //handle file opening error
    if(OpenFile == NULL){
        printf("file opening error");
        exit(1);
    } 

    //code that gets repeated

    fclose(openFile);
}

getch();

---

2) You can instead write a function and call it twice (here I'm sending file name as argument)

void my_function(char* file_name)
{
    char character;
    int lineCount, wordCount, charCount;

    lineCount = 0;
    wordCount = 0;
    charCount = 0;

    openFile = fopen(file_name, "r");

    //handle file opening error
    if(OpenFile == NULL){
        printf("file opening error");
        exit(1);
    }

    //code that gets repeated

    fclose(openFile);
}

//your main

int main (void) {
    char fileName1[1500] = "", fileName2[1500] = "";

    printf("Enter the first filename: ");
    gets(fileName1);
    my_function(fileName1);

    printf("Enter the second filename: ");
    gets(fileName2);
    my_function(fileName2);

    getch();
}  

---

3)You can use both loop and function!

void my_function(char* file_name)
{
    //body of the function same as in before example
}

//your main

int main (void) {
    char fileName[1500] = "";

    for(int i = 1; i <= 2; i++){
        printf("Enter the %d filename: ", i);
        gets(fileName);
        my_function(fileName);
    }

    getch();
}