How to create a C Ranking?

Question

How can I read and sort a text file where the information is like this:

  carlos   5 
  lucas   20 
  josue   10 

*On file it looks like this.

Saved randomly but when I read the precise information it is in the order of who has the most points for the least points.

I use the following code to read the file itself :

void ranking(){         



     system("cls");
     printf("\n ######- Ranking de Jogadores -######\n");
     printf("  \n");
     printf(" NOME - PONTOS \n");
     printf("  \n");
     printf(" ");


  char texto_str[999];
  char usuario[20];

  //abrindo o arquivo_frase em modo "somente leitura"
  pont_arq = fopen("ranking.txt", "r");

 while(fgets(texto_str, 20, pont_arq) != NULL)
 printf("%s \n ", texto_str);



  fclose(pont_arq);

  getch();

system("PAUSE");
carregaMenu();

}

Answer 1

To get the names and punctuation, as the size of the name and punctuation characters are different, we can use fscanf to accomplish this task.
We would have for example:

fscanf(pont_arq, "%s %d\n", nome, &pontuacao);

As for the ordination we would have several ways to accomplish this task. I think the right way would be for you to create a priority list data structure and a player struct by inserting them in an orderly way in this list. You could also add to the list anyway and use a sorting algorithm (Sort) like bubblesort, heapsort, quicksort, using as a score sort parameter.

Another way maybe simpler but less organized would be you work with a vector of names, another vector with the scores corresponding to the names and so sort the two vectors using punctuation as parameter of ordering.

I will perform an implementation of the last option cited because it is the simplest. I also used bubblesort as the sorting algorithm. I decided to do it in a static way, but if it is not possible to define the line size of the file use malloc to perform the players dynamic instantiation.

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


//algoritmo de sort, perceba que aqui eu ordeno os dois vetores (nome e pontuação)

void bubbleSort(int* pontuacao, char nomes[10][255], int tamanho)
{   
    int i;
    int trocou;
    do  
    {
        trocou = 0;
    for (i=tamanho; i > 0; i--)
    {   
        if (pontuacao[i] > pontuacao[i-1]) 
        {   
            int pAux;
            char nAux[255];
            pAux = pontuacao[i];
            strcpy(nAux, nomes[i]);
            pontuacao[i] = pontuacao[i-1];
            strcpy(nomes[i], nomes[i-1]);
            pontuacao[i-1] = pAux;
            strcpy(nomes[i-1], nAux);
            trocou = 1;
        }   
    }   

    }while (trocou);
}   



void ranking(){         

    //system("clear");
    printf("\n ######- Ranking de Jogadores -######\n");
    printf("  \n");
    printf(" NOME - PONTOS \n");
    printf("  \n");

    // cria ponteiro de arquivo
    FILE * pont_arq;
    //abrindo o arquivo_frase em modo "somente leitura"
    pont_arq = fopen("data.txt", "r");
    // cria matriz para 10 nomes (poderia ser dinamico) e array de pontuações
    char nomes[10][255];
    int pontuacoes[10];
    //variaveis que irá receber o nome ea pontuação do arquivo
    char nome[255];
    int pontuacao;
    //quantidade de jogadores
    int tamanho = 0;

    //lê do arquivo
    while(fscanf(pont_arq, "%s   %d\n", nome, &pontuacao) != EOF)
    {   
        strcpy(nomes[tamanho],nome);
        pontuacoes[tamanho] = pontuacao;
        tamanho++;  
    }

    //Ordena
    bubbleSort(pontuacoes, nomes, tamanho);

    //Imprime
    int i;
    for (i=0; i<tamanho; i++)
    {
        printf("%s %d\n", nomes[i], pontuacoes[i]);
    }

  fclose(pont_arq);

  //getch();

//system("PAUSE");
//carregaMenu();

}