program v C načítanie z textu

1)

• C standard library (EN)
• taký nejaký základ (SK)
• Učebnica jazyka C (SK kniha)

2)

char world[height][width];

Taka definicia v C kóde nesmie byť! Je to chyba, reálne sa nealokuje alebo nemusí, alebo nemusí dostatočné. Nie je to správne podľa štandartu C. V C++ to môžeš použiť, ale nie v C.

Napríklad (lepšie by bolo pole reťazcov načítavať zo súboru a ukladať):

/*
 * WARNING !!!
 *     - write for unix like system
 * 
 *  - in Microsoft Windows is end line with chars '\r' '\n'
 *  - in older MAC OS is end line with chars '\r' '\r'
 */
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAX_W 15
#define MAX_H 15

int main(){
    FILE *f;
    int height;
    int width;
    char pismeno;
    unsigned char world[MAX_W][MAX_H];

    /* open file */
    f=fopen("ahoj","r");
    if(f == NULL)
    {
        perror("file 'open'");
        return 1;
    }

    /* read width */
    if(fscanf(f,"%d",&width) != 1)
    {
        perror("read width");
        fclose(f);
        return 1;
    }

    /* read height */
    if(fscanf(f,"%d",&height) != 1)
    {
        perror("read height");
        fclose(f);
        return 1;
    }

    /* configuration and data in file are separate with new line */
    pismeno=fgetc(f);
    if(pismeno == EOF)
    {
        perror("read data");
        fclose(f);
        return 2;
    }
    if(pismeno != '\n')
    {
        fputs("error input - no separate configure and data in file", stderr);
        fclose(f);
        return 2;
    }
        
    /* read line */
    for(int i=0;i<height;i++)
    {
        /* read chars on line */
        for(int j=0;j<width;j++)
        {
            pismeno=fgetc(f);
            if(pismeno == EOF)
            {
                perror("read data");
                fclose(f);
                return 2;
            }
            world[i][j]=pismeno;
        }
        
        pismeno=fgetc(f);
        if(pismeno != '\n')
        {
            putchar(pismeno);
            fputs("bad char in input", stderr);
            fclose(f);
            return 3;
        }
    }
    
    printf("\n\n");

    /* print array */
    for(int i=0;i<height;i++)
    {
        for(int j=0;j<width;j++)
        {
            putchar(world[i][j]);
        }
        putchar('\n');
    }
    fclose(f);

    return 0;
}

Frekvenčná analýza

#include <stdio.h>

/*
 * Iba pre ANSI kodovanie na 8 bitov. Nefunguje napr. pre UTF-8, UTF-16.
 * 
 * Rozlisuje velkost pisma
 */
void frequency_analyze(unsigned char **array, int height, int width)
{
    /* Ak je jeden definovane, ostatne su nastavene na 0 - standart c.
     * Inac:
     *         1) definovat menovanim vsetkych prvkov pola
     *         2) pouzit funkciu bzero (alebo memset)
     */
    size_t frequency[256]={0};
    int i,j;
    
    if(x < 0 || y < 0)
    {
        fputs("error frequency analyze", stderr);
        return;
    }
    
    /*
     *  vykona analyzu
     */
    for(i=0;i<x;i++)
        for(j=0;j<y;j++)
            frequency[array[i][j]]++;
    
    /*
     *  vypise analyzu
     */
    puts("no-show chars:");
    for(i=0; i<32; i++)
        printf("%d %n\n", i, frequency[i]);
    puts("show chars:");
    for(;i<256; i++)
        printf("'%c' %n\n", i, frequency[i]);
}

int main()
{
    unsigned char data[4][3]=
    {
        {'a', 'n', 'o'},
        {'n', 'i', 'e'},
        {'j', 'o', 'j'},
        {'a', 'c', 'h'},
    };
    
    frequency_analyze(data, 4, 3);
    return 0;
}