C Programming

Practise Exercise 9A: File Handling

1. Define an input file handle called input_file, which is a pointer to a type FILE.


	FILE *input_file;

2. Using input_file, open the file results.dat for read mode.


	input_file = fopen( "results.dat", "r" );

3. Write C statements which tests to see if input_file has opened the data file successfully. If not, print an error message and exit the program.


	if( input_file == NULL ) {
		printf("Unable to open file.\n");\
		exit(1);
	}

4. Write C code which will read a line of characters (terminated by a \n) from input_file into a character array called buffer. NULL terminate the buffer upon reading a \n.


	int ch, loop = 0;

	ch = fgetc( input_file );
	while( (ch != '\n') && (ch != EOF) ) {
		buffer[loop] = ch;
		loop++;
		ch = fgetc( input_file );
	}
	buffer[loop] = NULL;

5. Close the file associated with input_file.


	fclose( input_file );