shows code to read a file into a correctly sized string buffer using malloc

fileToString.c

// adapted from stackoverflow post: http://stackoverflow.com/questions/3233645/read-multiples-lines-from-file-to-a-string-in-c/3233744#3233744 by user http://stackoverflow.com/users/346905/faisal
char * readFile( const char * fileName ) {
      // open the file
        FILE* fp = fopen( fileName, "r");

        if (fp == NULL) {
                fprintf(stderr,"ERROR: couldn't open file\n");
                exit(1);
        }

        // seek to the end to get the length
        // you may want to do some error-checking here
        fseek(fp, 0, SEEK_END);
        long length = ftell(fp);

        // we need to seek back to the start so we can read from it
        fseek(fp, 0, SEEK_SET);

        // allocate a block of memory for this thing
        // the +1 is for the nul-terminator
        char* buffer = (char *)malloc((length + 1) * sizeof(char));

        if (buffer == NULL) {
                fprintf(stderr,"ERROR: not enough memory to read file\n");
                exit(1);
        }

        // now for the meat. read in the file chunk by chunk till we're done
        long offset = 0;
        while (!feof(fp) && offset < length) {
                offset += fread(buffer + offset, sizeof(char), length-offset, fp);
        }

        // buffer now contains your file
        // but if we're going to print it, we should nul-terminate it
        buffer[offset] = '\0';

        // always close your file pointer
        fclose(fp);

        return buffer;
} // end function