[Courses] [C] lesson13: The last two exercises, done :)

[Morgon Kanter]

First, on the ascii-to-binary and the binary-to-ascii. 

/******* BEGIN ASCII-TO-BINARY ********/
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>

int main(int argc, char *argv[]) {
    FILE *input_file, *output_file;
    char input[80];
    long long in;

    if(argc != 3) {
        fprintf(stderr, "Error: Incorrect number of arguments\n");
        fprintf(stderr, "Usage: asciibin inputfile outputfile\n");
        exit(8);
    }

    input_file = fopen(argv[1], "r");
    if(errno == ENOENT) {
        fprintf(stderr, "Error: Unable to open %s\n", argv[1]);
        exit(8);
    }
    output_file = fopen(argv[2], "w");
    if(output_file == NULL) {
        fprintf(stderr, "Error: Unable to open %s for writing\n", argv[2]);
        exit(8);
    }

    fgets(input, sizeof(input), input_file);
    in = atoll(input);

    fwrite(&in, 1, sizeof(in), output_file);

    fclose(input_file);
    input_file = NULL;
    fclose(output_file);
    output_file = NULL;
    
    puts("Done");
    return 0;
}
/****** END ASCII-TO-BINARY *******/
Okay, it read from an input-file: 33
It outputted to a file: !^@^@^@^@^@^@^@ (approximation, kedit couldn't handle 
that ;)

Now to translate it back:
/******* BEGIN BINARY-TO-ASCII *******/
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>

int main(int argc, char *argv[]) {
    FILE *input_file, *output_file;
    long long input;
    char output[10];

    if(argc != 3) {
        fprintf(stderr, "Error: improper number of arguments\n");
        fprintf(stderr, "Usage: binascii inputfile outputfile\n");
        exit(8);
    }
    
    /* Open files and check for errors */
    input_file = fopen(argv[1], "r");
    if(errno == ENOENT) {
        fprintf(stderr, "Error: Unable to open %s for reading\n", argv[1]);
        exit(8);
    }
        output_file = fopen(argv[2], "w");
    if(output_file == NULL) {
        fprintf(stderr, "Error: Unable to open %s for writing\n", argv[2]);
        exit(8);
    }
    
    fread(&input, 1, sizeof(input), input_file);
    sprintf(output, "%lli", input);
    fputs(output, output_file);

    puts("Done");

    return 0;
}
/******* END BINARY-TO-ASCII ********/
The input: the same as last one's output
The output: 33, the same as the first one's input. See, it works :)

-----------------------------------------------------------------------
And the last exercise, write a program to copy one file to another file but 
remove the high bit (0x80). First, I wrote a small program to write the "high 
bit" to a file along with a couple of other things. Now here is the 
un-highbit program:

/******* BEGIN UN-HIGHBIT *******/
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>

int main(int argc, char *argv[]) {
    FILE *input_file, *output_file;
    char current_char;

    if(argc != 3) {
        fprintf(stderr, "Error: incorrect number of arguments\n");
        fprintf(stderr, "Usage: unhighbit infile outfile\n");
        exit(8);
    }

    input_file = fopen(argv[1], "r");
    if(errno == ENOENT) {
        fprintf(stderr, "Error: couldn't open %s for reading\n", argv[1]);
        exit(8);
    }
    output_file = fopen(argv[2], "w");
    if(output_file == NULL) {
        fprintf(stderr, "Error: couldn't open %s for writing\n", argv[2]);
        exit(8);
    }

    current_char = fgetc(input_file);
    while(current_char != EOF) {
        if((current_char & 0x80) != 0) goto end_of_loop;
        
        fputc(current_char, output_file);
     
        end_of_loop:
        current_char = fgetc(input_file);
    }

    fclose(input_file);
    input_file = NULL;
    fclose(output_file);
    output_file = NULL;

    puts("Done");

    return 0;
}
/********* END UN-HIGHBIT *********/
The input file read the following:
Yo[highbit]Cya
Output file then read:
YoCya

End of lesson13 :)

Morgon
--
grab my updated (11/25/02) public key from http://www.surgo.net/pubkey.asc