Hi,
Again, this is NOT a difficulty but for anyone wanting to comment.
And this is for P. 38 Exercise 1-14
Initially, this gave me the dreaded Segmentation Fault (aka Access
Violation). It was naturally something to do with the array. I was
exceeding the permissible index maximum.
My solution:
#include <stdio.h>
int main() {
#define MAX_LENGTH 26 /* English alphabet has 26 letters */
int char_freqs[MAX_LENGTH];
int i;
for (i = 0; i < MAX_LENGTH; ++i)
char_freqs[i] = 0;
/* fill in the frequencies array, char_freqs
* Lowercase and uppercase of same letter treated as one letter
*/
char c;
while ((c = getchar()) != EOF) {
if ((c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z')) {
/* in ASCII table 'a' > 'A' */
/* i.e. if lowercase */
if (c >= 'a')
++char_freqs[c - 'a'];
else ++char_freqs[c - 'A'];
}
}
/* display the histogram */
int j;
for (i = 0; i < MAX_LENGTH; ++i) {
/* select lowercase as heading for each bar */
printf("%c \t", i + 'a');
for (j = 1; j <= char_freqs[i]; ++j)
printf("#");
printf("\n");
}
return 0;
}
Why I was receiving access violations:
if (c >= 'a')
++char_freqs[c - 'a'];
else ++char_freqs[c - 'A'];
Exchanging 'a' with 'A' in the above causes the program to attempt to
write to array indices that fall beyond the highest index. The OS
responds by sending a signal (SIGSEGV) to terminate the program
immediately.
Edward
On 21/06/2016, Edward Bartolo <edbarx@???> wrote:
> Hi,
>
> This is NOT a difficulty. I am posting my code so that anyone wanting
> to comment can do so.
>
> Pg 38, Exercise: 1-13
> Write a program to print a histogram of the lengths of words in its
> input. Horizontal bars selected.
>
> My solution/code:
>
> #include <stdio.h>
>
> int main() {
> #define MAX_LENGTH 10
>
>
> int word_sizes[MAX_LENGTH];
>
> int i;
> for (i = 0; i < MAX_LENGTH; ++i)
> word_sizes[i] = 0;
>
> /* fill in the frequencies array, word_sizes */
> char c;
> int ws = 0;
> while ((c = getchar()) != EOF) {
> if (c == ' ' || c == '\n' || c == '\t') {
> if (ws > 0) {
> if (ws > MAX_LENGTH) {
> printf("\nMAX_LENGTH execeeded, exiting.\n");
> return -1;
> }
> ++word_sizes[ws];
> }
> ws = 0;
> }
> else ++ws;
> }
>
> /* display the histogram */
> int j;
> for (i = 0; i < MAX_LENGTH; ++i) {
> printf("%d chars\t", i);
> for (j = 1; j <= word_sizes[i]; ++j)
> printf("#");
> printf("\n");
> }
>
> return 0;
> }
>
> Edward
>
::
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