Thread: Read a file with filenames

Hi!

I'm making a program which reads a file which contains names of files. Then, I have to call a function that opens these files.

I made this piece of code (clarification: I put 3 in the looping considering that there are only 3 namefiles in the file).

Code:

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

void read_file(char* name){  
    FILE *file;
    file=fopen(name,"r");
    if(file==NULL){
        printf("We couldn't open the file\n");
        exit(1);
    }   
}

int main(){

    char name[50];
    char aux[50];
    int i;
    FILE* file;

    printf("Insert the file with filenames: ");
    scanf("%s\n",name);

    file=fopen(name,"r");
    if(file==NULL){
        printf("We couldn't open the filee\n");
        exit(1);
    }  

    for(i=0;i<3;i++){
        fscanf(file,"%[^\n]\n",aux);
        read_file(aux);
    }  
}

However, I am still unable to open the files because the function doesn't works.

I'd be grateful if someone could help me.

Thank you very much,
OlgaFontae.

Several problems:

I would use fgets() instead of scanf() to read in filenames, but you would need to remove the newline at the end of the string input.

Code:

// Instead of:
scanf("%s\n",name);
// Use:
scanf(" %s", name);

You assume there at least three filenames in the file entered. Could there be more or less than three filenames???


In the function: "read_file(char* name)" you open the file but do nothing, and you do not close the file before exiting.

Make these changes until the code works, then add the processing of the files in read_file().

Thank you for answering my question.

For this particular case, the file only contains three filenames.

I make your suggested changes to my code and now the program opens the file with the filenames.
However, the filenames contained do not open yet.

Waiting to your reply,
Thank you very much.,
OlgaFontae.

Hi again,

I copy your code and it doesn't work.

I'll post the content of the file I tried with.

mydog.txt
mycat.txt
myhorse.txt

I think the error might have to do something with removing the end of line character ('\n'), but it shouldn't be read with fscanf, so I have no idea.

Thank you again,
OlgaFontae.

Originally Posted by OlgaFontae

Hi again,

I copy your code and it doesn't work.

I'll post the content of the file I tried with.

mydog.txt
mycat.txt
myhorse.txt

I think the error might have to do something with removing the end of line character ('\n'), but it shouldn't be read with fscanf, so I have no idea.

Thank you again,
OlgaFontae.

My code works fine on Linux with gcc 12.

What compiler & O/S are you using?

As I said, you might want to switch to fgets() rather than scanf().

It's always better to break down a task into smaller tasks
Maybe you can work with this skeleton

Code:

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

void read_file(char* name){
    printf("Filename received: %s\n", name);
    // TO DO add your logic
}

void process_file(char *name)
{
    printf("Processing: %s", name);
    // TO DO 
    // open file and read all filenames using read_line 
    // send each filename to read_file 
}

char *read_line(char *buffer, int buf_size, FILE *stream)
{
    if(!fgets(buffer, buf_size, stream))
        return NULL;
    char *pos = strchr(buffer, '\n');
    if(pos)
        *pos = '\0';
        
    return buffer;
}


int main()
{
    char name[256] = "";
    printf("Enter filename: ");
    read_line(name, 255, stdin);
    process_file(name);
}