How to make an appointment in C language?

Question

Good evening, I’m doing a little project of writing binary files in a txt and then reading these files. But I have to read the file or list them all. How could I do a search for the necessary file? And one more question what is the feof? List the last data, I wanted to list by search, type type the name and query. 1-Let’s assume that I record the song "In the end" from Linkin park...and then record other songs. I wanted that when I pressed on consult, I typed the name of the song in case "In the end" and returned the data only of my query

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

struct{
char nome[30];
char banda[40];
float valor;
}musica;

void escreveMusica()
{
 char numstr[8];

FILE *fptr;

if((fptr=fopen("Musicas","wb"))==NULL){

    printf("Não posso abrir arquivo...Musicas");//Caso nao consiga abrir
    exit(1);
}
do{
    fflush(stdin);
    printf("\n Digite o nome da musica: ");
    gets(musica.nome);
    printf("\n Digite o nome da banda: ");
    gets(musica.banda);
    printf("\n Digite o preco: ");
    gets(numstr);
    musica.valor=atof(numstr);
    fwrite(&musica,sizeof(musica),1,fptr);
    printf("\n Adiciona outro registro no arquivo..");
 }
while(getchar()=='s');
fclose(fptr);   
 }

void listarMusicas(){   
 char numstr[8];

FILE *fptr;
if((fptr=fopen("Musicas","rb"))==NULL){
    printf("Nao posso abrir arquivo... Musicas");
    exit(1);
}
printf("\nDados da consulta:\n");
while(fread(&musica, sizeof(musica),1,fptr)==1){//Pegar todas As     
listagens
    printf("\n Nome: %s\n",musica.nome);
    printf("\n Banda: %s\n",musica.banda);
    printf("\n Preco: %.2f\n",musica.valor);
    printf("\n--------------------\n");
}
fclose(fptr);       
           }

void consultarMusica(){ //Lista o ultimo dado, eu queria listar por
char numstr[8];             pesquisa, tipo digitar o nome e listar 

FILE *fptr;
if((fptr=fopen("Musicas","rb"))==NULL){
    printf("Nao posso abrir arquivo... Musicas");
    exit(1);
}
printf("\nDados da consulta:\n");

    printf("\n Nome: %s\n",musica.nome);
    printf("\n Banda: %s\n",musica.banda);
    printf("\n Preco: %.2f\n",musica.valor);
    printf("\n--------------------\n");

fclose(fptr);       
           }

int main()
{
int scan;

do{

printf("Selecione a opcao desejada\n1.Para comprar musica\n2.Para 
consultar todas as musicas compradas\n3.Consultar Ultima   
Musica\n0.Sair\n");
scanf("%d",&scan);

switch(scan){

case 1: escreveMusica();
system("cls");
break;
case 2: listarMusicas();
printf("\n");
break;
case 3: consultarMusica();
printf("\n");
break;
case 0: break;  
default: 
printf("Opcao Invalida");
}

}
while(scan!=0);

 return 0;
 }

Answer 1

If you want to fetch data on for a query within a file, I recommend using fwrite and the fread, because it will write the exact bytes to your structure, thus facilitating your search.

Entering data:

typedef struct __musica{
    char nome[64];
    char banda[64];
    float valor;
}musica;

The music structure has a fixed size, so it can be seen with the sizeof

void inserir(musica *m, FILE *f){
    fwrite(m, sizeof(musica), 1, f); // escreve a estrutura no arquivo
}

Searching for data:

musica *busca_p_nome(FILE *f, const char *nome){
    musica *m = malloc(sizeof(musica));
    fseek(f, SEEK_SET, 0); // vai até o inicio do arquivo
    while(!feof(f)){
        fread(m, sizeof(musica), 1, f); // le a estrutura do arquivo
        if(!strcmp(m->nome,nome)) // compara o nome da musica com o nome da musica desejada
             return m; // retorna a musica se encontrar
    }

    return NULL; // se não encontrar a musica retorna Nulo
}

To insert the songs without deleting the existing ones, the file must contain the parameter "a" to be opened. fopen("lista.txt", "a"), the a represents Append To File.

The feof means End Of File (the first letter represents that it belongs to the file method, so feof), when it reaches the end of the file it returns 1, Otherwise 0.

That’s why you wear !feof(arquivo) on parole.