storing text file contents into a string

This is a discussion on storing text file contents into a string within the C Programming forums, part of the General Programming Boards category; I've wrote a program that takes a text file in as a string, and encrypts it, using my own, very ...

  1. #1
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    storing text file contents into a string

    I've wrote a program that takes a text file in as a string, and encrypts it, using my own, very weak, encryption key. The program works, as long as the text file contains only a single word, with no spaces. I'm assuming for some reason it doesn't like spaces. My code is as follows

    Code:
    #include <stdio.h>
    #include <string.h>
    
    
    int main (int argc, char *argv[])
    {
      FILE *in;
      FILE *out;
      char buf[512];
      char secret[512];
      int x;
       
      in = fopen ( argv[1], "r" );
      out = fopen (argv[2], "w+" );
    
      if ( in == NULL ) {
        perror ( "Unable to open the file" );
      }
    
      /* Read a string */
      fread ( buf, 1, sizeof buf, in );
      printf ( "%s\n", buf );
    
      /*pre programm processesing and beautifying*/
      system("clear");
      printf("\n\n");
    
    
       for (x = 0; x < 512; x++) { //begin for loop
       switch(buf[x])
       {  //begin switch/case
       
       // encryption key hidden for security reasons
    
       }  //end switch/case
       }  //end for loop
    
    
    
      fprintf(out, "%s\n", secret);  
      fclose ( in );
      fclose (out);
    
    
      printf("%s\n", secret);
    
    
    
       printf("\n\n");
    } //end main
    If anyone could recommend any modifications, I'd appreciate it.
    Michael

  2. #2
    Gawking at stupidity
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    Ahh, you have to love security by obscurity. I don't see why it would only handle single words with the code you've shown. Are you sure your encryption isn't changing a space into '\0'?

    When you print the string right after reading it does it print the whole string or only 1 word? Please explain what you mean by "it only works when it's 1 word".

    And also:
    Code:
    for (x = 0; x < 512; x++) { //begin for loop
    Gee, ya think?
    If you understand what you're doing, you're not learning anything.

  3. #3
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    ok, by "it only works with one word", i mean, if i use a line of text that includes a space, the text file created by the program, is completely empty.

  4. #4
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    ok, i have that part figured out, but now i have a new question. When I store the text file into a string, I think that setting the string to 512 bytes, it automatically fills in the rest of the 512 bytes if the text file does not fill the buffer. Is there a way to do a SIZEOF file.txt? or something to that end?

  5. #5
    Gawking at stupidity
    Join Date
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    Why not use the return value of fread()? It tells you how many items it read.
    You could do:
    Code:
    {
      size_t data_len;
    
      data_len = fread ( buf, 1, sizeof buf, in );
    }
    If you understand what you're doing, you're not learning anything.

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