使用fscanf在C中读取多行

Question

i'm currently doing an uni project which has to read a multiple lines sequence of inputs given in a .txt format. This is my first experience with C, so i don't know much about reading files with fscanf and then processing them. The code i wrote goes like this:

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

int main() {
    char tipo [1];
    float n1, n2, n3, n4;
    int i;
    FILE *stream;
    stream=fopen("init.txt", "r");
    if ((stream=fopen("init.txt", "r"))==NULL) {
        printf("Error");
    } else {
        i=0;
        while (i<4) {
            i++;
//i know i could use a for instead of a while
            fscanf(stream, "%s %f %f %f %f%", &tipo, &n1, &n2, &n3, &n4);
            printf("%s %f %f %f %f", tipo, n1, n2, n3, n4);
        }
    }
    return 0;
}

My "init" file is formatted like this:

L 150.50 165.18 182.16 200.50
G 768.12 876.27 976.56 958.12
A 1250.15 1252.55 1260.60 1265.15
L 200.50 245.30 260.10 275.00
A 1450.15 1523.54 1245.17 1278.23
G 958.12 1000.65 1040.78 1068.12

I don't know how to tell the program to skip a line after the first one is read.

Thanks for the help in advance!

Answer 1

Use fscanf(stream, "%*[^\\n]\\n") to skip line. Just add one if statement to check line number to skip. if (i == 2) to skip second line. Also change char tipo[1] to char tipo and change "%s" to "%c" in printf and fscanf

while (i++ < 4) 
{
    if (i == 2) // checks line number. Skip 2-nd line
    {
        fscanf(stream, "%*[^\n]\n");
    }
    fscanf(stream, "%c %f %f %f %f\n", &tipo, &n1, &n2, &n3, &n4);
    printf("%c %f %f %f %f\n", tipo, n1, n2, n3, n4);
}

Also you are opening file twice. if(streem = fopen("init.txt", "r") == NULL) will be true because you have already opened file.

Answer 2

In response to " I don't know how to tell the program to skip a line after the first one is read ."Just do this!

while (i<4) 
{
    i++;
    //i know i could use a for instead of a while
    fscanf(stream, "%s %f %f %f %f%", &tipo, &n1, &n2, &n3, &n4);
    if(i != 2) //skipping second line
        printf("%s %f %f %f %f", tipo, n1, n2, n3, n4);

}

Also there is no point in using an 1-element array. If you wish to just use a char element change it from char tipo [1]; to char tipo; and your respective "%s" to "%c" . But if you wish it to be a string element : change it from char tipo [1]; to char *tipo; or char tipo [n]; and keep your "%s" .

Answer 3

There's no reason to use a char array (string) when you're only going to read one character.

Do this:

char tipo;

and

fscanf(stream, "%c %f %f %f %f%", &tipo, &n1, &n2, &n3, &n4);

and you're code should work. Note the c instead of s.