Reading the whole text file into a char array in C

FILE *fp;long lSize;char *buffer;fp = fopen ( "blah.txt" , "rb" );if( !fp ) perror("blah.txt"),exit(1);fseek( fp , 0L , SEEK_END);lSize = ftell( fp );rewind( fp );/* allocate memory for entire content */buffer = calloc( 1, lSize+1 );if( !buffer ) fclose(fp),fputs("memory alloc fails",stderr),exit(1);/* copy the file into the buffer */if( 1!=fread( buffer , lSize, 1 , fp) )  fclose(fp),free(buffer),fputs("entire read fails",stderr),exit(1);/* do your work here, buffer is a string contains the whole text */fclose(fp);free(buffer);

A solution in the form of a complete program that answers the question and demonstrates it. It is a bit more explicit than other answers and, therefore, easier to understand for those less experienced in C (IMHO).

#include <stdio.h>#include <stdlib.h>#include <stdbool.h>/* * 'slurp' reads the file identified by 'path' into a character buffer * pointed at by 'buf', optionally adding a terminating NUL if * 'add_nul' is true. On success, the size of the file is returned; on * failure, -1 is returned and ERRNO is set by the underlying system * or library call that failed. * * WARNING: 'slurp' malloc()s memory to '*buf' which must be freed by * the caller. */long slurp(char const* path, char **buf, bool add_nul){    FILE  *fp;    size_t fsz;    long   off_end;    int    rc;    /* Open the file */    fp = fopen(path, "rb");    if( NULL == fp ) {        return -1L;    }    /* Seek to the end of the file */    rc = fseek(fp, 0L, SEEK_END);    if( 0 != rc ) {        return -1L;    }    /* Byte offset to the end of the file (size) */    if( 0 > (off_end = ftell(fp)) ) {        return -1L;    }    fsz = (size_t)off_end;    /* Allocate a buffer to hold the whole file */    *buf = malloc( fsz+(int)add_nul );    if( NULL == *buf ) {        return -1L;    }    /* Rewind file pointer to start of file */    rewind(fp);    /* Slurp file into buffer */    if( fsz != fread(*buf, 1, fsz, fp) ) {        free(*buf);        return -1L;    }    /* Close the file */    if( EOF == fclose(fp) ) {        free(*buf);        return -1L;    }    if( add_nul ) {        /* Make sure the buffer is NUL-terminated, just in case */        buf[fsz] = '\0';    }    /* Return the file size */    return (long)fsz;}/* * Usage message for demo (in main(), below) */void usage(void) {    fputs("USAGE: ./slurp <filename>\n", stderr);    exit(1);}/* * Demonstrates a call to 'slurp'. */int main(int argc, char *argv[]) {    long  file_size;    char *buf;    /* Make sure there is at least one command-line argument */    if( argc < 2 ) {        usage();    }    /* Try the first command-line argument as a file name */    file_size = slurp(argv[1], &buf, false);    /* Bail if we get a negative file size back from slurp() */    if( file_size < 0L ) {        perror("File read failed");        usage();    }    /* Write to stdout whatever slurp() read in */    (void)fwrite(buf, 1, file_size, stdout);    /* Remember to free() memory allocated by slurp() */    free( buf );    return 0;}

Since I used slurp() expecting it to work, a few days later I found out that.... it doesn't.

So for people that are eager to copy/paste a solution to "getting the contents of a FILE into a char*", here's something you can use.

char* load_file(char const* path){    char* buffer = 0;    long length;    FILE * f = fopen (path, "rb"); //was "rb"    if (f)    {      fseek (f, 0, SEEK_END);      length = ftell (f);      fseek (f, 0, SEEK_SET);      buffer = (char*)malloc ((length+1)*sizeof(char));      if (buffer)      {        fread (buffer, sizeof(char), length, f);      }      fclose (f);    }    buffer[length] = '\0';    // for (int i = 0; i < length; i++) {    //     printf("buffer[%d] == %c\n", i, buffer[i]);    // }    //printf("buffer = %s\n", buffer);    return buffer;}