CODEWITHSUNDEEP
creadfile
Marcus Abrate
Marcus Abrate

Reputation: 3

Reading reads strings from keyboard and writing them to a file

Here's my task and below you can find my specific question and the code I wrote:

Write a program that reads strings and writes them to a file. The string must be dynamically allocated and the string can be of arbitrary length. When the string has been read it is written to the file. The length of the string must be written first then a colon (‘:’) and then the string. The program stops when user enters a single dot (‘.’) on the line.

For example:

User enters: This is a test Program writes to file: 14:This is a test

Question:

My code adds the number of characters and the colon, but not the string I typed, and when entered "." it wont exit

This is the code I have so far:

#pragma warning(disable: 4996)

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

#define MAX_NAME_SZ 256

int main() {

    char key[] = ".";

    char *text;
    int i;

    text = (char*)malloc(MAX_NAME_SZ);

    FILE* fp;

    do {
        printf("Enter text or '.' to exit: ", text);
        fgets(text, MAX_NAME_SZ, stdin);

        for (i = 0; text[i] != '\0'; ++i);

        printf("%d: %s", i);

        fp = fopen("EX13.txt", "w");

        while ((text = getchar()) != EOF) {
            putc(text, fp);
        }

        fclose(fp);
        printf("%s\n", text);


    } while (strncmp(key, text, 1) != 0);
    puts("Exit program");


    free(text);

    return 0;
}

Upvotes: 0

Views: 373

Answers (2)

Filip Emanuel Drexler
Filip Emanuel Drexler

Reputation: 46

I think this should work for strings that are shorter than 255 chars.

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

#define MAX_NAME_SZ 256


int main()
{
     
     char key[] = ".\n";
     char *text;

     text = (char*)malloc(MAX_NAME_SZ);
     if (text == NULL)
     {
             perror("problem with allocating memory with malloc for *text");
             return 1;
     }

     FILE *fp;
     fp = fopen("EX13.txt", "w");
     if (fp == NULL)
     {
             perror("EX13.txt not opened.\n");
             return 1;
     }

     printf("Enter text or '.' to exit: ");
     while (fgets(text, MAX_NAME_SZ, stdin) && strcmp(key, text))
     {
             fprintf(fp, "%ld: %s", strlen(text) - 1, text);
             printf("Enter text or '.' to exit: ");
     }

     free((void *) text);
     fclose(fp);

     puts("Exit program");

     return 0;
}

Upvotes: 1

Jabberwocky
Jabberwocky

Reputation: 50774

There are many issues in your code, almost everything is wrong.

Just a few problems:

  • You use printf("%d: %s", i); to print on the screen what should go into the file.
  • The loop while ((text = getchar()) != EOF) doesn't make any sense.
  • You're closing the file after the first line entered
  • You ignore all compiler warnings
  • The end condition while (strncmp(key, text, 1) != 0) is wrong, you're only testing if the string starts with a ., and you're testing it too late.

This could be a start:

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

#define MAX_NAME_SZ 256

int main() {
  char* text;
  int i;

  text = (char*)malloc(MAX_NAME_SZ);

  FILE* fp;
  fp = fopen("EX13.txt", "w");
  if (fp == NULL)
  {
    printf("Can't open file\n");
    exit(1);
  }

  do {
    printf("Enter text or '.' to exit: ");
    fgets(text, MAX_NAME_SZ, stdin);

    if (strcmp(".\n", text) == 0)
      break;

    for (i = 0; text[i] != '\0' && text[i] != '\n'; ++i);

    fprintf(fp, "%d: %s", i, text);

  } while (1);

  fclose(fp);

  puts("Exit program");
  free(text);
  return 0;
}

There is a limitation though, in this program the maximum line length is 254 characters, not including the newline character. As far as I understood, the line length must be arbitrary.

I let you do this on your own as an exercise, but at your C knowledge level it will be hard.

Upvotes: 2

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