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!
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 and
printf.
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
echo_digits.c which print the digit
characters (only) in its command line arguments.
The only function you can use is printf.
For example:
./echo_digits 42 23skid00 a5a5a5a hi 42 2300 555
Your tutor may still choose to cover some of the questions time permitting.
letter_triangle.c that read an positive
integer n and outputs a triangle of letters of height
n as below. For example:
./letter_triangle
Enter height: 3
A
BCB
DEFED
./letter_triangle
Enter height: 7
A
BCB
DEFED
GHIJIHG
KLMNONMLK
PQRSTUTSRQP
VWXYZABAZYXWV
./letter_triangle
Enter height: 10
A
BCB
DEFED
GHIJIHG
KLMNONMLK
PQRSTUTSRQP
VWXYZABAZYXWV
CDEFGHIJIHGFEDC
KLMNOPQRSRQPONMLK
TUVWXYZABCBAZYXWVUT
input_statistics.c that for the
characters provided on standard input:
For example:
./input_statistics
"Beauty is truth, truth beauty," -- that is all
Ye know on earth, and all ye need to know.
Input contains 27 blanks, tabs and new lines
Number of words: 19
Length of shortest word: 2
Length of longest word: 8
./input_statistics
And here is another example with only one line of input!!!!!!!!!
Input contains 11 blanks, tabs and new lines
Number of words: 11
Length of shortest word: 2
Length of longest word: 14
matrix below hold?
#include <stdio.h>
#define N_ROWS 12
#define N_COLUMNS 15
int main(void) {
int matrix[N_ROWS][N_COLUMNS];
}
Write nested loops that set every element of matrix.
Each element should be set to the product of its two indices.
Write nested loops that print the elements of
matrix plus sums of each row and sums of each column.
The output of your code should look like this:
./matrix
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 | 0
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 | 105
0 2 4 6 8 10 12 14 16 18 20 22 24 26 28 | 210
0 3 6 9 12 15 18 21 24 27 30 33 36 39 42 | 315
0 4 8 12 16 20 24 28 32 36 40 44 48 52 56 | 420
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 | 525
0 6 12 18 24 30 36 42 48 54 60 66 72 78 84 | 630
0 7 14 21 28 35 42 49 56 63 70 77 84 91 98 | 735
0 8 16 24 32 40 48 56 64 72 80 88 96 104 112 | 840
0 9 18 27 36 45 54 63 72 81 90 99 108 117 126 | 945
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 | 1050
0 11 22 33 44 55 66 77 88 99 110 121 132 143 154 | 1155
---------------------------------------------------------------------------
0 66 132 198 264 330 396 462 528 594 660 726 792 858 924
#include <stdio.h>
#define N 10
int main(void) {
int digit_count[N];
int x, last_digit;
while (scanf("%d", &x) == 1) {
last_digit = x % N;
digit_count[last_digit] = digit_count[last_digit] + 1;
}
last_digit = 0;
while (last_digit < N) {
printf("%d numbers with last digit %d read\n", digit_count[last_digit], last_digit);
last_digit = last_digit + 1;
}
return 0;
}
It works on the students laptop:
gcc -Wall -O last_digit.c a.out 42 121 100 11 1 numbers with last digit 0 read 2 numbers with last digit 1 read 1 numbers with last digit 2 read 0 numbers with last digit 3 read 0 numbers with last digit 4 read 0 numbers with last digit 5 read 0 numbers with last digit 6 read 0 numbers with last digit 7 read 0 numbers with last digit 8 read 1 numbers with last digit 9 read
But when run at uni, it fails:
dcc last_digit.c a.out 42 121 100 11 778121076 numbers with last digit 0 read 7632239 numbers with last digit 1 read -2032569224 numbers with last digit 2 read 32727 numbers with last digit 3 read 0 numbers with last digit 4 read 0 numbers with last digit 5 read -2032409578 numbers with last digit 6 read 32727 numbers with last digit 7 read -21600000 numbers with last digit 8 read 32767 numbers with last digit 9 read
Why doesn't the code work at uni?
Why doesn't dcc detect an error?
Fix the code (make sure you understand how it works - it's a common and useful programming pattern).
int nums1[10];
int nums2[] = {0,1,2,3,4,5,6,7,8,9};
int nums3[10] = {0,2,4,6,8,-2};
int nums4[10] = {0};
int nums5[2][10] = {{0,1,2,3,4,5,6,7,8,9},
{10,20,30,40,50,60,70,80,90,100}};
printf("%d\n",nums2[3]);
printf("%d\n",nums3[5]);
printf("%d\n",nums5[0][1]);
printf("%d\n",nums5[1][0]);
nums1[0] = nums2[1] + 10 ;
printf("%d\n",nums1[0]);
int i = 0;
printf("%d\n",nums1[i]);
printf("%d\n",nums2[10]);
printf("%d\n",nums5[2][0]);
printf("%d\n",nums5[1][10]);