C cannot open text file

Question

I tried to make a program that tells you how many words, lines and characters are in a text file, but the function fopen() fails to open the file. I tried both absolute and relative paths to the text file but I get the same output. Can you please tell me what's wrong?

My compiler is gcc version 4.6.3 (Linux)

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define N 256

void tokenize(const char *filename)
{
    FILE *f=NULL;
    char line[N],*p;
    unsigned long int ch=0,wd=0,ln=0;
    int t;
    f=fopen(filename,"rt");
    if(f==NULL)
    {
        perror("The following error occurred");
        exit(1);
    }
    fgets(line,N,f);
    while(!feof(f))
    {
        ln++;
        p=strtok(line," ");
        while(p!=NULL)
        {
            wd++;
            t=strlen(p);
            ch+=t;
            printf("Word number %lu with length %d: %s\n",wd,t,p);
            p=strtok(NULL," ");
        }
        fgets(line,N,f);
    }
    printf("%lu lines, %lu words, %lu characters\n",ln,wd,ch);
    fclose(f);
}

int main(void)
{
    char filename[80];
    size_t slen;
    printf("Enter filename path:\n");
    fgets(filename,80,stdin);
    slen = strlen (filename);
    if ((slen > 0) && (filename[slen-1] == '\n'))
         filename[slen-1] = '\0';
    printf("You have entered the following path: %s\n",filename);
    tokenize(filename);
    return 0;
}

output:

Enter filename path:
input.txt
You have entered the following path: input.txt

The following error occurred: No such file or directory

pb2q · Answer 1 · 2012-08-21T16:32:23.557

4

You've retained the newline character from the input in your filename. You can see this when you echo the filename in your output: notice the blank line.

You'll need to strip off this newline before you pass it to your function. There are a few ways to do this, here's one:

size_t idx = strlen(filename);
if ((idx > 0) && filename[idx - 1] == '\n')
    filename[idx - 1] = '\0';

edited Aug 21 '12 at 16:32

answered Aug 21 '12 at 04:15

pb2q

58,613
19
146
147

score 2 · Accepted Answer · edited May 23 '17 at 12:20

You need to remove the trailing newline character from your string, with something like:

size_t slen = strlen (filename);
if ((slen > 0) && (filename[slen-1] == '\n'))
    filename[slen-1] = '\0';

And, while I applaud your use of fgets for user input (since it can be protected from buffer overflow), there's still a couple of edge cases you haven't considered, such as when the line is too long, or the user flags end of input). See here for a more robust solution.

score 1 · Answer 3 · answered Jan 30 '13 at 19:01

1

You can declare a function like:

void rmnewline(char *s)
{
int l=strlen(s);
if(l>0 && s[l-1]=='\n')
   s[l-1]='\0';
}

and call it before using your char array.

answered Jan 30 '13 at 19:01

user12410214

21
2

C cannot open text file

3 Answers3