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Q: Write a program to print a histogram of the frequencies of different characters in its input.
A:
#include <stdio.h>
int main(void)
{
int FREQUENCY_LENGTH = 256; // We'll just count all ASCII values. Why not?
int frequencies[FREQUENCY_LENGTH];
int i, j, c;
int tally = 0;
for (i = 0; i < FREQUENCY_LENGTH; ++i) {
frequencies[i] = 0;
}
// This part gets a lot more simple.
while ((c = getchar()) != EOF) {
++frequencies[c];
}
printf("\n");
printf("Character Frequencies\n");
printf("---------------------\n");
/* For the sake of brevity, we will only print visible characters.
* The ASCII values for visible characters are all between 33 and 126,
* a fact I pulled off www.asciitable.com
*/
for (i = 33; i <= 126; ++i) {
printf("%c | ", i);
for (j = 0; j < frequencies[i]; ++j) {
printf("-");
}
printf("\n");
}
return 0;
}
America! Land of my dreams, home of the Whopper!
(ctrl+d)
Character Frequencies
---------------------
! | --
" |
# |
$ |
% |
& |
' |
( |
) |
* |
+ |
, | -
- |
. |
/ |
0 |
1 |
2 |
3 |
4 |
5 |
6 |
7 |
8 |
9 |
: |
; |
< |
= |
> |
? |
@ |
A | -
B |
C |
D |
E |
F |
G |
H |
I |
J |
K |
L | -
M |
N |
O |
P |
Q |
R |
S |
T |
U |
V |
W | -
X |
Y |
Z |
[ |
\ |
] |
^ |
_ |
` |
a | ---
b |
c | -
d | --
e | -----
f | --
g |
h | ---
i | -
j |
k |
l |
m | ----
n | -
o | ----
p | --
q |
r | ---
s | -
t | -
u |
v |
w |
x |
y | -
z |
{ |
| |
} |
~ |
Q: The same as part one, but vertical.
A:
#include <stdio.h>
int main(void)
{
int FREQUENCY_LENGTH = 10;
int frequencies[FREQUENCY_LENGTH];
int i, j, c;
int tally = 0;
int highest = 0;
// We're tallying in the exact same way.
for (i = 0; i < FREQUENCY_LENGTH; ++i) {
frequencies[i] = 0;
}
while ((c = getchar()) != EOF) {
if (c == '.' || c == '\n' || c == '\t' || c == ' ' || c == ',') {
if (tally > FREQUENCY_LENGTH) {
tally = FREQUENCY_LENGTH - 1;
}
++frequencies[tally];
tally = 0;
} else {
++tally;
}
}
/* First, we need the height of the highest bar.
* At the top of the function, temp is set to zero. Normally a function
* wouldn't be this long, but we haven't got to that part fo the book yet.
*/
for (i = 0; i < FREQUENCY_LENGTH; i++) {
if (frequencies[i] > highest) {
highest = frequencies[i];
}
}
/* Now we keep drawing the bars untill our 'highest' variable, and everything
* in our tallies is zeroed out.
*/
while (highest) {
// Remember there are no zero-length words so we skip 0. Feel free to play
// around with this, because some junk data is getting stored in
// frequencies[0]. Why?
for(i = 1; i < FREQUENCY_LENGTH; i++) {
if (frequencies[i] == highest) {
printf(" | ");
frequencies[i]--;
} else {
printf(" ");
}
}
printf("\n");
highest--;
}
/* Now we print a handy guide at the bottom.
*/
for (i = 1; i < FREQUENCY_LENGTH; i++) {
printf("---");
}
printf("-\n");
for (i = 1; i < FREQUENCY_LENGTH; i++) {
if (i == FREQUENCY_LENGTH - 1) {
printf(" %d+", i);
} else {
printf(" %d ", i);
}
}
printf("\n");
return 0;
}
The worst of misery
Is when a nature framed for noblest things
Condemns itself in youth to petty joys,
And, sore athirst for air, breathes scanty life
Gasping from out the shallows.
Supercalifragilisticexpialidocious.
(ctrl+d)
|
| |
| | |
| | | |
| | | | | | |
| | | | | | |
| | | | | | | | |
----------------------------
1 2 3 4 5 6 7 8 9+
You can play around with this quite a bit. Removing one line and then changing one character, and we get a nice little graph:
.
.
.
.
. . .
. .
----------------------------
1 2 3 4 5 6 7 8 9+
Q: What does the 'typedef' keyword do exactly?
A: 'typedef' lets you define a type, which is to say, it lets you give a new name to a pre-existing type (which can be useful for organizational/readability purposes), or to define a struct as a new type, unique to your program.
Q: Write a program to print a histogram of the lengths of words in its input. It is easy to draw the histogram with the bars horizontal; a vertical orientation is more challenging.
A:
#include <stdio.h>
int main(void)
{
/* Because of screen space and the limitations of terminal output, words
* longer than ten are going to be categorized as greater than 10.
*
* In this model, frequencies[0] is a one-character word, and frequencies[1]
* is a two-character word. This 'off-by-one' behaviour seems unintuitive
* and certainly leads to bugs, but there is a very good, low-level reason
* that becomes very obvious when you learn a bit of assembly. You could find
* a work-around (like leaving frequencies[0] unused), but it's better to get
* use to thinking of things as starting with the 0th element because, in the
* long run, there's no real avoiding it in programming.
*/
int FREQUENCY_LENGTH = 10;
// It's tradition to capitalize this we won't be changing.
int frequencies[FREQUENCY_LENGTH];
int i, j, c;
int tally = 0;
/* Initialize all frequencies to 0 */
/* The book hasn't told us this yet, but the easiest way to initiate all
* elements in an array to 0 is simply to go:
* int frequencies[10] = {0};
* BUT doing it with what the book has tought us gives us a better feel for
* the way that arrays work.
*/
for (i = 0; i < FREQUENCY_LENGTH; ++i) {
frequencies[i] = 0;
}
/* Count word-length frequencies */
/* I'm missing colons and semi-colons here for the sake of space, but you get
* the drift. In a professional setting, you would probably want to create
* a separate subroutine called is_word_barrier() to keep your code cleaner
* and more readable, but we haven't got to that part of the book yet.
*/
while ((c = getchar()) != EOF) {
if (c == '.' || c == '\n' || c == '\t' || c == ' ' || c == ',') {
if (tally > FREQUENCY_LENGTH) {
tally = FREQUENCY_LENGTH - 1;
}
++frequencies[tally];
tally = 0;
} else {
++tally;
}
}
/* Print horizontal-barred histogram */
printf("\n");
printf("Word Frequencies: Horizontal\n");
printf("----------------------------\n");
for (i = 0; i < FREQUENCY_LENGTH; ++i) {
if (i != 0) {
if (i == FREQUENCY_LENGTH - 1) {
printf("%3d+ | ", i);
} else {
printf("%3d | ", i);
}
for (j = 0; j < frequencies[i]; ++j) {
printf("-");
}
printf("\n");
}
}
return 0;
}
The worst of misery
Is when a nature framed for noblest things
Condemns itself in youth to petty joys,
And, sore athirst for air, breathes scanty life
Gasping from out the shallows.
Supercalifragilisticexpialidocious.
(ctrl+d)
Word Frequencies: Horizontal
----------------------------
1 | -
2 | ----
3 | -------
4 | -----
5 | ---
6 | ------
7 | ---
8 | ---
9+ | -
Q: Write a program that prints its input one word per line.
A:
#include <stdio.h>
int main(void)
{
char c;
while ((c = getchar()) != EOF) {
if (c == '\t' || c == '\n' || c == ' ') {
printf("\n");
} else {
putchar(c);
}
}
return 0;
}
> muh muh muh moo cows
muh
muh
muh
moo
cows
