🔹 Exercise File Programming

 

🔹 Example Problem 1: Write to a File

✅ Using Built-in Functions

#include <stdio.h>

int main() {
    FILE *fp;
    char text[100];

    fp = fopen("output.txt", "w");  
    if (fp == NULL) {
        printf("Error opening file!\n");
        return 1;
    }

    printf("Enter a line of text: ");
    fgets(text, sizeof(text), stdin);   // built-in function

    fputs(text, fp);  // built-in function
    fclose(fp);

    printf("Data written successfully.\n");
    return 0;
}

---

🚀 Without Built-in String Functions (manual copy)

#include <stdio.h>

int main() {
    FILE *fp;
    char text[100];
    int i = 0;

    fp = fopen("output.txt", "w");
    if (fp == NULL) {
        printf("Error opening file!\n");
        return 1;
    }

    printf("Enter a line of text: ");
    while ((text[i] = getchar()) != '\n' && i < 99) {  // manual input
        i++;
    }
    text[i] = '\0';

    // write manually character by character
    for (int j = 0; text[j] != '\0'; j++) {
        fputc(text[j], fp);
    }

    fclose(fp);
    printf("Data written successfully.\n");
    return 0;
}

---

🔹 Example Problem 2: Count Characters, Words, Lines

✅ Using Built-in Functions (isspace)

#include <stdio.h>
#include <ctype.h>

int main() {
    FILE *fp;
    char ch;
    int characters = 0, words = 0, lines = 0, inWord = 0;

    fp = fopen("output.txt", "r");
    if (fp == NULL) {
        printf("File not found!\n");
        return 1;
    }

    while ((ch = fgetc(fp)) != EOF) {
        characters++;
        if (ch == '\n') lines++;

        if (isspace(ch)) {     // built-in function
            inWord = 0;
        } else if (!inWord) {
            inWord = 1;
            words++;
        }
    }

    fclose(fp);

    printf("Characters: %d\nWords: %d\nLines: %d\n", characters, words, lines);
    return 0;
}

---

🚀 Without Built-in Functions (isspace replaced manually)

#include <stdio.h>

int isSpace(char c) {  // manual implementation
    return (c == ' ' || c == '\n' || c == '\t');
}

int main() {
    FILE *fp;
    char ch;
    int characters = 0, words = 0, lines = 0, inWord = 0;

    fp = fopen("output.txt", "r");
    if (fp == NULL) {
        printf("File not found!\n");
        return 1;
    }

    while ((ch = fgetc(fp)) != EOF) {
        characters++;
        if (ch == '\n') lines++;

        if (isSpace(ch)) {   // using custom function
            inWord = 0;
        } else if (!inWord) {
            inWord = 1;
            words++;
        }
    }

    fclose(fp);

    printf("Characters: %d\nWords: %d\nLines: %d\n", characters, words, lines);
    return 0;
}