Function scanf with variable amount of parameters, how to implement?

One way is to use normal reading by adapting to needs, something like this:

char arquivo[] = "1 2 3 4 5";
int a, b, c, d, e;
sscanf (arquivo, "%d %d %d %d %d", &a, &b, &c, &d, &e);
printf ("%d - %d - %d - %d - %d", a, b, c, d, e);

See running on ideone .

Obviously you need to use fscanf() which is the correct one for file and not the one I used for easy.

Another possibility, seems to me to be , if you do not want to create all the variables and make reading easier it would read one by one in a loop. Something like this:

int i = 0;
int tamanho = 5;
int array[tamanho];
FILE * arquivo = fopen("file.txt", "r");
while (fscanf(arquivo, "%d", &array[i++]) == 1);

See running on CodingGround .

You can also do this in variable length lists with vfscanf() giving you more flexibility, if you specify the format of the data that will be received in each of the positions. I've never used it and do not have the details, but the documentation provides this example:

#include <stdio.h>
#include <stdbool.h>
#include <stdarg.h>

bool checked_sscanf(int count, const char* buf, const char *fmt, ...)
{
    va_list ap;
    va_start(ap, fmt);
    int rc = vsscanf(buf, fmt, ap);
    va_end(ap);
    return rc == count;
}

int main(void)
{
    int n, m;

    printf("Parsing '1 2'...");
    if(checked_sscanf(2, "1 2", "%d %d", &n, &m))
        puts("success");
    else
        puts("failure");

    printf("Parsing '1 a'...");
    if(checked_sscanf(2, "1 a", "%d %d", &n, &m))
        puts("success");
    else
        puts("failure");
}

Well if you want to read through the end of the file do so:

#include<stdio.h>

int main(){
    int a[30], n = 0;

    while(scanf("%d", &a[n++]) != EOF && n < 30)
        printf("a[%d] = %d, ", n-1, a[n-1]);
}

Scanf returns EOF when it arrives at the end of the file and you do not have anything else to read, comparing this you know when the file is finished!

  

Entry:
  2 4 23
  55 12

     

Output:
  a [0] = 2, a [1] = 4, a [2] = 23, a [3] = 55, a [4] = 12,

If you just want to read until you finish the line, it gets a bit more complicated:

#include<stdio.h>

int main(){
    int a[30], n = 0, c;
    char linha[512], *plin;

    scanf("%510[^\n]", linha);
    plin = linha;

    while(sscanf(plin, "%d%n", &a[n++], &c) != EOF && n < 30){
        printf("a[%d] = %d, ", n-1, a[n-1]);
        plin += c;
    }
}

  

Entry:
  2 4 23
  55 12

     

Output:
  a [0] = 2, a [1] = 4, a [2] = 23,

Notice that this time he only read the first line. Scanf% d will not tell you when you skipped a line, it just swallows and line and moves on to the next one. So if you read only the first line with the limiter% [^ n], which reads until you find a \ n and then use sscanf on that line, you can only read the integers of the line!

Remembering that I have put a maximum of 30 numbers, you can increase the limit or make a malloc if 30 is not enough.

Just like you used scanfTeste.exe < arquivo.txt to run the program. The right thing would be to open the file and use it with fscanf