Is it possible to open the file for writing and at the same time open for reading without before closing in C?

Question

Is it possible to open the file for writing and at the same time open for reading without before closing in C?

Asked 5 years, 2 months ago

Viewed 196 times

2

Not a good programming practice?

void leitura(FILE *arq)
{
  if((arq = fopen("dificuldade.txt","r")) == NULL)
    printf("Erro ao abrir o arquivo\n"); 
  else
  {
    //linhas de codigo
    fclose(arq); 
  }
}

void impressao(FILE *arq)
{
  int i;

  if((arq = fopen("dificuldade.txt","w")) == NULL)
    printf("Erro ao abrir o arquivo\n");
  else
  {
    for(i=0; i<10; i++)
       {
         //linhas de codigos
         leitura(arq); 
         //Estou no loop e quero fazer a leitura a cada impressão
         //Cada impressão no ciclo, quero ler e manipular aqueles dados
         //Como faço isso, pois tenho que fechar o arquivo... ?
       }
    fclose(arq);
  }
}

main()
{
  FILE *arq;
  impressao(arq);
  return 0;
}

You should use "r+", to read and write, preserving the original content

– FourZeroFive

2019/04/12 at 18:58
On all put "r+" and the "fclose" stays where it is? without closing the file during printing to then read?

– Misaee 21

2019/04/12 at 19:02
Opens the file only once with "r+", and works with fputs(), fgets() and etc..

– FourZeroFive

2019/04/12 at 19:09
If after writing you want to go back to the beginning of the file use the Rewind function.

– anonimo

2019/04/12 at 19:47

1 answer

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by Fábio Morais • **1,522** points · Answer 1 · 2019-04-14T00:50:39+00:00

It is good practice to close every time you open a text file. With the attached table you can see some features you can implement to read and write.

These functions below are used to read and write to the text file.

void fprintf (FILE *fluxo, char *formatação, ...);
int fwrite (void *dados, int tamanho_do_elemento, int num_elementos, FILE *fluxo);

More information about text files Wikibooks