scanf not recognises %59[^\n]

Question

Hello all what i am trying to do is to scanf a string to 2 struct variables but when running the code it simply passes though the scanf (both of them) and goes to the printf.

My code is the following:

struct s_Especialidade{
    char nome[60];
    char descricao[60];
    struct s_Especialidade *proximo;
};

typedef struct s_Especialidade Especialidade;
typedef Especialidade *PESPECIALIDADE; 

void novaEspecialidade()
{
    PESPECIALIDADE novo = malloc(sizeof(Especialidade) );
    int opcao=0;
    printf("\nNome: ");
    scanf("%59[^\n]\n", (novo->nome));
    printf("\nDescricao: ");
    scanf("%59[^\n]\n", (novo->descricao));
    novo->proximo = NULL;
    printf("\n%s - %s",novo->nome, novo->descricao);
}

Answer 1

The trouble is that white space (including newlines) in scanf() format strings behaves peculiarly — it means an arbitrary sequence of white space characters.

When it prompts Nome:, you can type a name ('Alexander the Great') and a newline, but the scanf() keeps reading until it comes across another character that isn't white space. So, you might type 'Conqueror of Asia', and then the prompt Descricao: will appear, and it will read until you type another character that isn't white space, and then it will terminate.

For example:

$ ./name-prompt
Nome: Alexander The Great 
Conqueror of Asia

Descricao: a

<<Alexander The Great>> - <<Conqueror of Asia>>
$

This is from the code:

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

struct s_Especialidade{
    char nome[60];
    char descricao[60];
    struct s_Especialidade *proximo;
};

typedef struct s_Especialidade Especialidade;
typedef Especialidade *PESPECIALIDADE; 

static
void novaEspecialidade(void)
{
  PESPECIALIDADE novo = malloc(sizeof(Especialidade) );
  printf("\nNome: ");
  if (scanf("%59[^\n]\n", (novo->nome)) != 1)
      printf("Oh, bother!\n");
  printf("\nDescricao: ");
  if (scanf("%59[^\n]\n", (novo->descricao)) != 1)
      printf("Oh, bother!\n");
  novo->proximo = NULL;
  printf("\n<<%s>> - <<%s>>\n", novo->nome, novo->descricao);
  free(novo);
}

int main(void)
{
  novaEspecialidade();
  return 0;
}

Note that the printf() output ends with a newline; that's generally a good idea.

To work around this, modify the scanf() format to:

"%59[^\n]"

After the scanf(), do the equivalent of:

int c;
while ((c = getchar()) != EOF && c != '\n')
    ;

Package it into a function — maybe gobble() or read_to_newline().

Or use fgets() to read the line and sscanf() to parse it; that often works better.

Answer 2

Are you trying to read 60 characters and indicating that by 59 in the scanf statement? Then, your scanf is wrong. Change it to: scanf ( "%s", novo->nome ); and it should work. Same with the other scanf.

Answer 3

Here is a complete example, reading two strings from stdin, then using sscanf to remove the trailing newline and printing them:

#include <stdio.h>

struct {
    char first[60];
    char second[60];
} store;

int main(int argc, char ** argv) {
    char buffer[60];

    printf("write something: ");
    fgets(buffer, 60, stdin);
    sscanf(buffer, "%s", store.first);

    printf("write something else: ");
    fgets(buffer, 60, stdin);
    sscanf(buffer, "%s", store.second);

    printf("you wrote: %s then %s\n", store.first, store.second);

    return 0;
}