C programming - Help with opening text file and reading from it

**juth93** · 10-13-2012

Hello! in my code i want to open a text file and then read/print out the content off the file.

this is my code:

Code:

int main()
{
    char s[20];
    FILE * fp;


    if((fp=fopen("bilar.txt", "r"))==NULL){
    printf("Error! opening file");
       exit(1);
    }
    fscanf(fp,"%s",s);
    printf("%s",s);


    fclose(fp);
    return 0;
}

it prints out 1

and here is the text file (bilar.txt)that i want the code to open and print out:

volvo 2003 lastbil
volgswagen 2009 personbil
peugot 1969 personbil
scania 2001 lastbil
chevrolet 1971 personbil
ferrari 1959 personbil

**Salem** · 10-13-2012

Well you need some kind of loop, such as

Code:

int ch;
while ( (ch=fgetc(fp)) != EOF ) {
}

while ( fscanf(fp,"%19s",s) == 1 ) {
}

while ( fgets( s, sizeof(s), fp ) != NULL ) {
}

It's really a question of whether you prefer to read the file
- character at a time
- word at a time
- line at a time

**bluechip** · 10-13-2012

You need to create three variables to read the contents of the file. 2 character arrays and one integer variable, say char model[20], int year, char last[20]
You will use a loop to read through the file
Something like this will work

Code:

  fscanf(fp,"%s%d%s",model,&year,last);
  printf("%s %d %s",model, year, last);
while ( !feof(fp) ) {
  fscanf(fp,"%s%d%s",model,&year,last);
  printf("%s %d %s",model, year, last);
}

**oogabooga** · 10-13-2012

Originally Posted by bluechip

You need to create three variables to read the contents of the file. 2 character arrays and one integer variable, say char model[20], int year, char last[20]
You will use a loop to read through the file
Something like this will work

Code:

  fscanf(fp,"%s%d%s",model,&year,last);
  printf("%s %d %s",model, year, last);
while ( !feof(fp) ) {
  fscanf(fp,"%s%d%s",model,&year,last);
  printf("%s %d %s",model, year, last);
}

That's wrong, bluetooth. Note that when the eof is hit you'll have an extra printf call. You presumably meant this:

Code:

while (fscanf(fp, "%19s %d %19s", model, &year, last) == 3) {
  printf("%s %d %s", model, year, last);
}

**bluechip** · 10-13-2012

Code:

fscanf(fp,"%s%d%s",model,&year,last);

while ( !feof(fp) ) {

  printf("%s %d %s",model, year, last);
  fscanf(fp,"%s%d%s",model,&year,last);

}

**AndiPersti** · 10-13-2012

That's still wrong. Read FAQ > Why it's bad to use feof() to control a loop - Cprogramming.com

Bye, Andreas

**bluechip** · 10-13-2012

@AndiPersti: Thanks for that! I learnt that way of controlling loops from the book 'C: How To Program Deitel'. I didn't know it was wrong!

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