[C] A better way for memory allocating

[Barakat]

Hello,

I've started learning C a few days ago and I wrote this simple code:

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

int main(void){

    char* tmp   = (char*) malloc(sizeof(char));
    int counter = 1;
    int fh  = open("file.txt", O_RDONLY);

    /* Ugly */
    while( read(fh, tmp, 1) != '\0' )
        counter++;

    lseek(fh, 0, SEEK_SET);
    char *buffer = (char*) malloc(sizeof(char) * counter);
    read(fh, buffer, counter);

    printf("%s", buffer);

    free(buffer);
    buffer = NULL;

    close(fh);

}

Does anyone know a better way to write it without that extra step (the counter)?

[Roxoff]

All you're doing is malloc'ing enough memory to contain the file - why don't you just check the file size?

Seek the end of the file:

fseek(fh, 0L, SEEK_END);

then find the current position of the file pointer

long int size = ftell(fh);

you can then use the 'size' to work out how much memory to allocate. Of course, as it's C, you'll have to declare the 'size' variable before you call ftell(...)

[theNbomr]

You can also call stat() against the filespec, or fstat() against the open filehandle, passing it a struct stat. The structure will be filled in with all sorts of goodies, including the size of the file, in bytes.

For details:

man 2 stat

--- rod.