File Handling Interview Questions

    Question 1: File Pointer

    Which type is used for file pointers in C?

    Question 2: fopen() Function

    Which is the correct syntax to open a file in C for reading?

    Question 3: fopen() Error Handling

    What will this program print if data.txt does not exist?

    #include <stdio.h>

int main() {
    FILE *fp;
    fp = fopen("data.txt", "r");
    if (fp == NULL)
        printf("File not found");
    else
        printf("File opened");
    return 0;
}

    Question 4: fprintf() Function

    What will this program do?

    #include <stdio.h>

int main() {
    FILE *fp = fopen("out.txt", "w");
    fprintf(fp, "Hello C");
    fclose(fp);
    return 0;
}

    Question 5: File Modes

    What does mode "a" do in fopen()?

    Question 6: fgetc() Function

    What will be the output if input.txt contains AB?

    #include <stdio.h>

int main() {
    FILE *fp = fopen("input.txt", "r");
    char ch = fgetc(fp);
    printf("%c", ch);
    fclose(fp);
    return 0;
}

    Question 7: fputc() Function

    What will this program do?

    #include <stdio.h>

int main() {
    FILE *fp = fopen("test.txt", "w");
    fputc('Z', fp);
    fclose(fp);
    return 0;
}

    Question 8: EOF Constant

    What does EOF stand for in C file handling?

    Question 9: fread() Function

    What does this code do?

    #include <stdio.h>

struct Data { int x; float y; };

int main() {
    struct Data d;
    FILE *fp = fopen("bin.dat", "rb");
    fread(&d, sizeof(d), 1, fp);
    fclose(fp);
    return 0;
}

    Question 10: fclose() Function

    Why should fclose() always be used after file operations?