Read lines from a file and create alphabetically sorted array

Question

I am learning C and I want to do this specific task. I know there is a number of similar questions and answers, but still... I will try to be more specific. Lets say, I have a file with following lines:

program01
programs
aprogram
1program
prog
5program

And I want now an array with:

1program
5program
aprogram
prog
program01
programs

So there are ONLY latin small letters and numbers in strings, no spaces. I know how to perform some separate steps, but want to get and feel the whole (and proper) concept, so to say. Probably it could make some sorting decisions on the fly when reading from file first? Manual sort is preferred for my particular case, just for the sake of better learning and possible optimisation. Lets say, maximal length of one line is 256, maximal number of lines is 256. Thanks in advance.

Answer 1

Check the below code:

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

int main(void) {
    char a[256][256];
    int i=0,j=0,k=0,n;

    while(i<256 && fgets(a[i],256,stdin) != NULL)
    {
        n = strlen(a[i]);
        if(n >0 && a[i][n-1] == '\n')
        a[i][n -1] = '\0';
        i++;
    }

    for(j=0;j<i;j++)
    {
        char max[256];
        strcpy(max,a[j]);
        for(k=j+1;k<i;k++)
        {
            if(strcmp(a[k],max) < 0)
            {
                char tmp[256];
                strcpy(tmp,a[k]);
                strcpy(a[k],max);
                strcpy(max,tmp);
            }
        }
        strcpy(a[j],max);
    }

    for(j=0;j<i;j++)
    {
        printf("%s\n",a[j]);
    }
    return 0;
}

Answer 2

The following cleanly compiles
however, I have not tested it

you might want to modify it to get the file name from 
the command line

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

#define MAX_ROWS (256)
#define MAX_COLUMNS (256)
#define FILE_NAME "myInputFile"

// prototypes
void bubbleSortWordsArray( int wordCount );
void printWordsArray( int wordCount );

static char words[MAX_ROWS][MAX_COLUMNS] = {{'\0','\0'}};

int main(void)
{
    FILE *fp = NULL;

    if( NULL == (fp = fopen( FILE_NAME, "r") ) )
    {
        perror( "fopen failed" );
        exit( EXIT_FAILURE );
    }

    // implied else, fopen successful

    // read each line from file into entry in words array
    int i = 0;
    while( fgets(words[i], MAX_COLUMNS, fp ) )
    {
        // remove trailing newline from string
        words[i][strlen(words[i])-1] = '\0';
        i++;
    }

     // 'i' contains number of valid entries in words[][]
    // sort the array of strings
    bubbleSortWordsArray(i);

    printWordsArray(i);

    return(0);
} // end function: main


void bubbleSortWordsArray( int wordCount )
{
    int c;  // outer index through rows
    int d;  // inner index through rows
    char swap[MAX_COLUMNS] = {'\0'};

    for (c = 0 ; c < ( wordCount - 1 ); c++)
    {
        for (d = 0 ; d <  (wordCount - c - 1); d++)
        {
            if(  0 > strcmp( words[d], words[d+1] ) )
            { // then words need to be swapped
                strcpy( swap, words[d]  );
                strcpy( words[d], words[d+1]);
                strcpy( words[d+1], swap );
            } // end if compare/swap
        } // end for
    } // end for each row
} // end function: bubbleSortWordsArray


void printWordsArray( int wordCount )
{
    int i; // loop index

    printf( "\n" ); // start on new output line
    for( i=0; i<wordCount; i++ )
    {
        printf( "%s\n", words[i] );
    }
} // end function: printWordsArray

Answer 3

Make a 2D char array try to read it by using fscanf function(sorry i cant remember the syntax). fscan will read your whole line till '\n' but there should not be space and store each string in a row. then sort it by comparaing the first index of each string