C File Reader from array

Question

I can see the last printf output of y but the fpc turns null.

I suspected for double quotes in fopen function but not could not find a solution: how to fix it?

Part of the code ;

char *y = &arr_lines[1024*2];

FILE *fpc = fopen(y, "r");

        if (fpc == NULL) {
                printf("Error opening file.\n");
                //return -1;
        }
printf("TEST %s\n",y);

When I run the code;

Error opening file.
TEST /Users/lessons/AbstractLesson.java

Here is the full code;

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#define LINESIZE 1024
int main(void){

    char *arr_lines, *line;
    char buf_line[LINESIZE];
    int num_lines = 0;
    char buf[10240];

    // open file
    FILE *fp = fopen("/tmp/file", "r");
    //FILE *fp1 = fopen(arr_lines, "r");
    if (fp == NULL) {
            printf("Error opening file.\n");
            return -1;
    }
    // get number of lines; from http://stackoverflow.com/a/3837983
    while (fgets(buf_line, LINESIZE, fp))
            if (!(strlen(buf_line) == LINESIZE-1 && buf_line[LINESIZE-2] != '\n'))
                    num_lines++;
    // allocate memory
    arr_lines = (char*)malloc(num_lines * 1024 * sizeof(char));
    // read lines
    rewind(fp);
    num_lines = 0;
    line=arr_lines;
    while (fgets(line, LINESIZE, fp))
            if (!(strlen(line) == LINESIZE-1 && line[LINESIZE-2] != '\n'))
                    line +=  LINESIZE;
    // print first four lines
    char *y = &arr_lines[1024*2];

    FILE *fpc = fopen(y, "r");
        //FILE *fp1 = fopen(arr_lines, "r");
        if (fpc == NULL) {
                printf("Error opening file.\n");
                //return -1;
        }

printf("TEST [%s]\n",y);
     //x = &arr_lines[1024*0];
    // y = *x;

  // finish
    fclose(fp);
    return 0;

}

Answer 1

Change printf("TEST %s\n", y) to printf("TEST \"%s\"\n", y) so we can see if you have any extra whitespace characters in the filename.

fgets() returns the new line, if it's there. I didn't see where your code clears the newline. Does your path string include the new line?

Beyond that, fopen() is almost certainly working correctly. The only options are 1) The path is not correct, 2) the path has whitespace or other invalid characters, or 3) the file is not available for reading.

If you don't have a new line in your path, then you simply haven't provided enough information to resolve this issue.

Answer 2

I suspect the path, /Users/lessons/AbstractLesson.java, is wrong. It looks like an OSX path and it might be missing the username between Users and lessons.