How to read names from a file and sort them in alphabetical order

raeiko

Hello guys, i need you help with a C program that reads names from a .txt file and sort them in alphabetical order. I have written the code for the reading part and it seems to work, but I don't know how to orgnize the bubble sort algorithm in order to compare strings and swap them. Could you please give me some hints? Thanks a lot, raeiko Here is my code:

#define SIZE 30

int main()
{
char name[ SIZE ]; /* Data records */

FILE \*fpPtr; /\* fpPtr = sorted\_file.txt pointer \*/

/\* fopen opens file; exits program if file cannot be opened \*/
if ( ( fpPtr = fopen( "sorted\_file.txt", "r" ) ) == NULL ) {
    printf( "File could not be opened\\n" );
} /\* End if \*/

/\* Read records from file \*/
else {
    printf( "%s\\n", "Name" );
    fscanf( fpPtr, "%s", name );
    
    /\* While not end of file \*/
    while( !feof( fpPtr ) ) {
            printf( "%s\\n", name );
            fscanf( fpPtr, "%s", name );
    } /\* End while \*/
    
    fclose( fpPtr ); /\* fclose closes the file \*/
    
} /\* End else \*/




return 0; /\* Indicates that the program terminated successfully \*/

} /* End Main */

Stuart Dootson

Why write your own bubble sort when the standard library has a quicksort built in. That way, you get a fast sort routine that you know works... 99.9999% of the time, it's better to use someone else's library code rather than write your own.

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

David Crow

Stuart Dootson wrote:

Why write your own bubble sort when the standard library has a quicksort built in.

Perhaps it's an academic exercise.

"Old age is like a bank account. You withdraw later in life what you have deposited along the way." - Unknown

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

Stuart Dootson

That's what I figured - in which case, helping him isn't helping him :-)

Java, Basic, who cares - it's all a bunch of tree-hugging hippy cr*p

David Crow

raeiko wrote:

...but I don't know how to orgnize the bubble sort algorithm in order to compare strings and swap them.

You first need to get a working bubble-sort algorithm before moving on.

int nNumbers[] = { 1, 7, 4, 10, 3, 5, 6, 9 };
int nCount = sizeof(nNumbers) / sizeof(nNumbers[0]);
...
BubbleSort(nNumbers, nCount);

Work on this, and when you get stuck, we'll be glad to help.

"Old age is like a bank account. You withdraw later in life what you have deposited along the way." - Unknown

"Fireproof doesn't mean the fire will never come. It means when the fire comes that you will be able to withstand it." - Michael Simmons

tyr2000

I think tree structer is far more better than the bubble sort in actual work, if you are doing a actual work not homework. there is less moving when the tree is used.

raeiko

Hello, I'm writing this program for an academical assignment that is why i need to use the bubble sort algorithm, even though, from what i undersand, is not the most suitable solution. I have tried to go on with my code but it's still not working and i'm getting more and more confused because i don't have really clear in my mind how to handle pointers... Here is what i have done but i'm sure it's completely wrong

/* Program that takes a text file as input and produces an output file that has all the original lines in alphabetical order */

#include <stdio.h>
#include <string.h>
#define SIZE 30

int main()
{
char name[ SIZE ]; /* Data records */

FILE \*fpPtr; /\* fpPtr = sorted\_file.txt pointer \*/

/\* fopen opens file; exits program if file cannot be opened \*/
if ( ( fpPtr = fopen( "sorted\_file.txt", "r" ) ) == NULL ) {
    printf( "File could not be opened\\n" );
} /\* End if \*/

/\* Read records from file \*/
else {
    printf( "%s\\n", "Name" );
    fscanf( fpPtr, "%s", name );
    
    /\* While not end of file \*/
    while( !feof( fpPtr ) ) {
            printf( "%s\\n", name );
            fscanf( fpPtr, "%s", name );
    } /\* End while \*/
    
    fclose( fpPtr ); /\* fclose closes the file \*/
    
} /\* End else \*/

/* sort */
for ( pass = 1; pass < SIZE; pass++ ){ /* loop to cotrol passes */
for ( counter = 0; counter < SIZE - 1; counter ++ ){ /* loop to control number of comparesons per pass */
if ( *name [ counter ] > *name [ counter + 1 ] ) {
hold = *name[ counter ];
*name[ counter ] = *name[ counter + 1 ];
*name[ counter + 1 ] = hold;
} /* End if */
}/* end of inner for */
}/* end of outer for */

return 0; /\* Indicates that the program terminated successfully \*/

} /* End Main */