Week 06 Tutorial Questions

The tutorial will start with a code review.
Your tutor has asked a lab pair to present their week 5 work.
Discuss the good, the bad and the ugly aspects of their code.
Please be gentle in any criticism - we are all learning!

What does the following function do?

int secret_function(char *word) {
    int i = 0;
    int result = 0;
    while (word[i] != '\0') {
        if(word[i] >= 'a' && word[i] <= 'z') {
            result++;
        }
        i++;
    }
    return result;
}

Can you explain the stopping case in the while loop? Why does it work and what is the significance of the '\0'?
What does the char *word input mean? What's the relationship between an array and a pointer?

Observe the following code, modified from lectures:

/* A Dice checking app
Marc Chee September 2019

This will take dice roll numbers from a user
and add them together.

It will then check if the roll total is higher
or lower than a secret target number
*/

#include <stdio.h>

#define EXIT_SUCCESS 0
#define SECRET_VALUE 7

int main(void) {
    int dieOne;
    int dieTwo;
    int diceSize = 6;
    
    // Ask the user for the size of the dice
    printf("How many sides are on the dice?\n");
    scanf("%d", &diceSize);
    
    // Get user input for dice rolls
    printf("Please type in the result of the first die:\n");
    scanf("%d", &dieOne);
    if (dieOne < 1 || dieOne >= diceSize) {
        printf("%d was invalid, ", dieOne);
        
        // Use mod to give a value inside the range 1-dice size
        dieOne = dieOne % diceSize;
        if (dieOne == 0) {
            dieOne = diceSize;
        }
        printf("and has been corrected to %d.\n", dieOne);
    }
    
    printf("Please type in the result of the second die:\n");
    scanf("%d", &dieTwo);
    if (dieTwo < 1 || dieTwo > diceSize) {
        printf("%d was invalid, ", dieTwo);
        
        // Use mod to give a value inside the range 1-dice size
        dieTwo = dieTwo % diceSize;
        if (dieTwo == 0) {
            dieTwo = diceSize;
        }
        printf("and has been corrected to %d.\n", dieTwo);
    }
    
    printf("You rolled %d and %d\n", dieOne, dieTwo);
    
    // create total and check against the secret number
    int total = dieOne + dieTwo;
    
    printf("The total is %d\n", total);
        
    if (total > SECRET_VALUE) {
        // total is higher than SECRET_VALUE
        printf("You succeeded!\n");
    } else if (total == SECRET_VALUE) {
        // total is tied with SECRET_VALUE
        printf("An exact tie!\n");
    } else {
        // total is lower than SECRET_VALUE
        printf("You failed!\n");
    }
    
    return EXIT_SUCCESS;
}

Discuss how we could make this code easier to read and safer to modify using functions. Suggest a function that would help and write that function.

Write a program sum_digits.c which reads characters from its input and counts digits.
When the end of input is reached it should print a count of how many digits occurred in its input and their sum.
The only functions you can use are getchar(), printf() and a very useful function called isdigit() from the ctype.h library which you should include.
For example:
```
./sum_digits
1 2 3 o'clock
4 o'clock rock
Input contained 4 digits which summed to 10
./sum_digits
12 twelve 24 twenty four
thirty six 36
Input contained 6 digits which summed to 18
```