COMP1511 Week 09 Tutorial Questions

No code review this week.
What is this week's blogging theme?

#include <stdio.h>

int main(void) {
    char str[10];
    str[0] = 'H';
    str[1] = 'i';
    printf("%s", str);
    return 0;
}

What will happen when the above program is compiled and executed?
How do you correct the program.

Name 3 errors in this program:

#include <stdio.h>

#define MAX_LINE 4096

int
main(void) {
    char line[MAX_LINE];
    int  i;

    while (fgets(line, MAX_LINE, stdin) != NULL) {
        i = MAX_LINE;
        while (line[i] != '\n') {
            i = i - 1;
        }
        printf("line %d characters long\n", i);
    }
    return 0;
}

Write a program line_length.c which reads lines from its input and prints how many characters each line contains.
The only functions you can use are fgets and printf.
You can assume lines contain at most 4096 characters.
For example:
```
./line_length
Andrew Rocks
line 12 characters long
A very long line.
line 17 characters long
short
line 5 characters long

line 0 characters long
```
What do you use fopen for and with what parameters?
Under what circumstances would fopen return NULL?
Write a C code to read in the first line of a file named data.txt and display it on the screen.
Write C code to read in a string from a user and write it to a file called data.txt. If the file data.txt exists, it should be overwritten
Write C to read in a string from a user and write it to a file called data.txt. If the file data.txt exists, it should append the line of text to the end of the file.

Revision questions
The remaining tutorial questions are primarily intended for revision - either this week or later in session.
Your tutor may still choose to cover some of the questions time permitting.
Write a program file_max.c that reads a set of integer numbers from a file and prints out the maximum number to standard output. The name of the input file should be specified as a command line argument.
Write a program strip_comments.c which reads lines from its input and prints them after removing any C // style comments. In another words if the line contains // it does not print the // or anything after it.
The only functions you can use are fgets and printf.
You can assume lines contain at most 4096 characters.
For example:
```
./strip_comments
     x = x + 1;  // This means add one to the variable x
     x = x + 1;
```
Also - is that a good comment to add to a C program?
Write a program filter_empty_lines.c which reads lines from its input and prints them only if they contain a non-white-space-character.
In another words remove lines are empty or contain only white-space.
The only functions you can use are fgets and printf.
You can assume lines contain at most 4096 characters.
You can assume there are only 3 white space characters, space, tab & new-line.
For example:
```
./filter_empty_lines
full line
full line
         
another no-empty line
another no-empty line
```

Write a C program reverse.c which reads lines and writes them out with the characters of each line in reverse order. It should stop when it reaches the end of input.

For example:

./reverse
The quick brown fox jumped over the lazy dog.
.god yzal eht revo depmuj xof nworb kciuq ehT
It was the best of times. It was the worst of times.
.semit fo tsrow eht saw tI .semit fo tseb eht saw tI
This is the last line.
.enil tsal eht si sihT
<control-d>

Revision questions