As a student with a background in Java, C#, a bit of Python and web-based languages, I am currently learning C. For practice I am coding a GTK application to convert a longer text to smaller pieces of text of 140 characters max. This use case is meant to post longer texts on Twitter easily.
So I experimented a bit and the application is working more or less at this moment. However, it regularly shows unexpected behaviour. When inserting text in the GTK interface (TextView) and clicking a button calling the below method, the output put back into the TextView sometimes looks like this:
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do
eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut eni
(1/4)
m ad minim veniam, quis nostrud exercitation ullamco laboris
nisi ut aliquip ex ea commodo consequat. Duis aute irure dolor in rep
(2/4)
(0/1981836649)
rehenderit in voluptate velit esse cillum dolore
eu fugiat nulla pariatur. Excepteur sint occaecat cupidatat non
proident, sunt in (3/4)
(0/1763734633)
(1701998412/544044403)
culpa qui officia deserunt mollit anim id est laborum. (4/4)
Or similar when inserting Lorem Ipsum as input. Sometimes it also cuts an entire part (e.g., only the (4/4) part is printed). The expected output is:
Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod
tempor incididunt ut labore et dolore magna aliqua. Ut eni (1/4)
m ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip > ex ea commodo consequat. Duis aute irure dolor in rep (2/4)
rehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur.
Excepteur sint occaecat cupidatat non proident, sunt in (3/4)
culpa qui officia deserunt mollit anim id est laborum. (4/4)
It applies to the following method, which is hooked to a GTK button:
void on_do_tweet_clicked()
{
char *text = get_text_from_text_view(g_tv_tweet_text);
int text_length = strlen(text);
int tweet_no = text_length / 130 + (text_length % 130 != 0);
char tweets[(int) tweet_no][140 * sizeof(char*)];
for (int i = 0; i < tweet_no; i++)
{
char *tweet = (char*) malloc(sizeof(char*) * 140);
if (tweet_no != 1) {
if (i + 1 == tweet_no) {
strcpy(tweet, &text[i * 130]);
} else {
strncpy(tweet, &text[i * 130], 130);
}
strcat(tweet, " (%d/%i)\n\0");
sprintf(tweets[i], tweet, i + 1, tweet_no);
} else {
strcpy(tweet, &text[i * 130]);
sprintf(tweets[i], tweet);
}
free(tweet);
}
free(text);
GtkTextBuffer *buffer = gtk_text_view_get_buffer((GtkTextView *) g_tv_tweet_text);
gtk_text_buffer_set_text(buffer, "", 0);
for (int i = 0; i < sizeof(tweets) / sizeof(tweets[0]); i++)
{
gtk_text_buffer_insert_at_cursor(buffer, tweets[i], strlen(tweets[i]));
}
memset(tweets, 0, sizeof(tweets));
}
I did some research on the problem and I suspect it has to do with either an problem with encodings or a problem related to pointers. However, my searches on the web did not result in a solution and my knowledge of C is still too limited to draw my own conclusions.
So here's the question: could anyone explain why this method is showing this behaviour and give me a hint on how to solve it?
Thank you in advance!
Thanks to #AnT I got it working. The final code is:
void on_do_tweet_clicked()
{
char *text = get_text_from_text_view(g_tv_tweet_text);
int text_length = strlen(text);
int tweet_no = text_length / 130 + (text_length % 130 != 0);
char tweets[(int) tweet_no][140 * sizeof(char)];
for (int i = 0; i < tweet_no; i++)
{
char *tweet = (char*) malloc(sizeof(char) * 140);
if (tweet_no != 1) {
if (i + 1 == tweet_no) {
strcpy(tweet, &text[i * 130]);
} else {
strncpy(tweet, &text[i * 130], 130);
}
tweet[130] = '\0';
strcat(tweet, " (%d/%i)\n");
sprintf(tweets[i], tweet, i + 1, tweet_no);
} else {
strcpy(tweets[i], &text[i * 130]);
}
free(tweet);
}
free(text);
GtkTextBuffer *buffer = gtk_text_view_get_buffer((GtkTextView *) g_tv_tweet_text);
gtk_text_buffer_set_text(buffer, "", 0);
for (int i = 0; i < sizeof(tweets) / sizeof(tweets[0]); i++)
{
gtk_text_buffer_insert_at_cursor(buffer, tweets[i], strlen(tweets[i]));
}
memset(tweets, 0, sizeof(tweets));
}
Related
Working on a CS class - C course problem. Part of the problem is to create a function to print the specified length from a char buffer, given a char pointer to print from.
Signature of the function to be called in loop:
bool printLine(char cbuffer, char *ptr, int bufferFillLength)
where cbuffer is the pointer to the beginning of the buffer, ptr is the pointer to the start of the string to print. Variable bufferFillLength is the number of characters to print from the buffer starting at ptr.
The function should be called in loop until the end of the line is reached (i.e function returns false).
Here is my attempt but not working and looking for help.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>
#define BUFFER_SIZE 300
bool printLine (char cbuffer, char *ptr, int printLength){
char *bufferprinttext;
strncpy (bufferprinttext, &cbuffer[ptr], printLength);
printf("%s", bufferprinttext);
if(bufferprinttext[strlen(bufferprinttext)-1] == '\n') {
//end of line reasched - return false;
return false;
}
return true;
}
int main(int argc, char *argv[])
{
char cbuffer[BUFFER_SIZE];
int printLength = 25;
bool isItEndOfBuffer = false;
int bufferCounter = 0;
cbuffer = "Fusce dignissim facilisis ligula consectetur hendrerit. Vestibulum porttitor aliquam luctus. Nam pharetra lorem vel ornare condimentum. Praesent et nunc at libero vulputate convallis. Cras egestas nunc vitae eros vehicula hendrerit. Pellentesque in est et sapien dignissim molestie.";
while(isItEndOfBuffer == false) {
++bufferCounter;
isItEndOfBuffer = printLine(cbuffer, &cbuffer[printLength * bufferCounter], printLength);
}
}
cbuffer is not a pointer as you say but is passed by value, thus you are not holding it's original reference as you seem to want. Try with the signature
bool printLine (char *cbuffer, char *ptr, int printLength);
Jonathan Leffler: I have update the code per your comment. The function prints now but truncated at the beginning. Couldn't figure out what I am missing.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>
#define BUFFER_SIZE 300
bool printLine (char cbuffer, char *ptr, int printLength){
for (int i = 0; i < printLength; i++) {
putchar(*ptr++);
if(*ptr == '\0') {
//end of line reasched - return false;
return true;
}
}
return false;
}
int main(int argc, char *argv[])
{
int printLength = 25;
bool isItEndOfBuffer = false;
int bufferCounter = 0;
char* cbuffer = "Fusce dignissim facilisis ligula consectetur hendrerit. Vestibulum porttitor aliquam luctus. Nam pharetra lorem vel ornare condimentum. Praesent et nunc at libero vulputate convallis. Cras egestas nunc vitae eros vehicula hendrerit. Pellentesque in est et sapien dignissim molestie.";
//printf ("cbuffer - start ptr=%p \n", &cbuffer[0]);
printf("Text to print:\n %s \n\n", cbuffer);
printf("But text is truncated at the begining by printLength(i.e. 25): \n");
//printf ("\nisItEndOfBuffer=%d \n", isItEndOfBuffer );
while( !isItEndOfBuffer ) {
++bufferCounter;
//printf ("ptr=%p \n", &cbuffer[printLength * bufferCounter]);
isItEndOfBuffer = printLine(*cbuffer, &cbuffer[printLength * bufferCounter], printLength);
//printf ("\nisItEndOfBuffer=%d \n", isItEndOfBuffer );
}
}
Output:
Text to print:
Fusce dignissim facilisis ligula consectetur hendrerit. Vestibulum porttitor aliquam luctus. Nam pharetra lorem vel ornare condimentum. Praesent et nunc at libero vulputate convallis. Cras egestas nunc vitae eros vehicula hendrerit. Pellentesque in est et sapien dignissim molestie.
But text is truncated at the begining by printLength(i.e. 25):
ligula consectetur hendrerit. Vestibulum porttitor aliquam luctus. Nam pharetra lorem vel ornare condimentum. Praesent et nunc at libero vulputate convallis. Cras egestas nunc vitae eros vehicula hendrerit. Pellentesque in est et sapien dignissim molestie.
I'm dealing with go/golang, trying to write code that takes a string and seed. It should return a shuffled string where the 1st and last letters in the word, punctuation and numbers are untouched.
Example:
my name is Nikki. My number is 333
should be
my nmae is Nkiki. My nebumr is 333
I'm very new to goland/go. Have tried to do it with rand.Shuffle:
func splitText(text string) []string {
re := regexp.MustCompile("[A-Za-z0-9']+|[':;?().,!\\ ]")
return re.FindAllString(text, -1)}
func scramble(text string, seed int64) string {
rand.Seed(seed)
split := splitText(text)
for i := range split {
e := split[i]
r := []byte(e)
for i := 0; i < len(r); i++ {
l := len(r) - 1
if i == 0 {
return string(r[0])
}
if i == l {
return string(r[l])
}
if i > 0 || i < l {
n := rand.Intn(l)
x := r[i]
r[i] = r[n]
r[n] = x
}
if (r[i] >= 32 && r[i] <= 62) || (r[i] >= 91 && r[i] <= 96) {
return string(r[i])
}
}
}
return text
}
func main() {
v := ("The quick brown fox jumps over the lazy dog.")
scramble(v, 100)
fmt.Println(scramble(v, 100))
}
But this returns only one letter and only if remoe f==0 or f==l, it doesn't hop to the next word.
I'm very new to goland/go.
Avoid writing programs in a new language as if you are still writing programs in an old language.
write code that takes a string and seed. It should return a shuffled
string where the 1st and last letters in the word, punctuation and
numbers are untouched.
Example:
my name is Nikki. My number is 333
should be
my nmae is Nkiki. My nebumr is 333
Here is a solution written in Go.
package main
import (
"fmt"
"math/rand"
"unicode"
)
func shuffle(word []rune, rand *rand.Rand) {
if len(word) < 4 {
return
}
chars := word[1 : len(word)-1]
rand.Shuffle(
len(chars),
func(i, j int) {
chars[i], chars[j] = chars[j], chars[i]
},
)
}
func scramble(text string, seed int64) string {
rand := rand.New(rand.NewSource(seed))
chars := []rune(text)
inWord := false
i := 0
for j, char := range chars {
if !unicode.IsLetter(char) {
if inWord {
shuffle(chars[i:j], rand)
}
inWord = false
} else if !inWord {
inWord = true
i = j
}
}
if inWord {
shuffle(chars[i:len(chars)], rand)
}
return string(chars)
}
func main() {
for _, text := range []string{
"my name is Nikki. My number is 333",
"The quick brown fox jumps over the lazy dog.",
loremipsum,
} {
fmt.Printf("%q\n", text)
fmt.Printf("%q\n", scramble(text, 100))
}
}
var loremipsum = `
Lorem ipsum dolor sit amet, consectetur adipiscing elit,
sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam,
quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur.
Excepteur sint occaecat cupidatat non proident,
sunt in culpa qui officia deserunt mollit anim id est laborum.
`
Playground: https://play.golang.org/p/NoHXynQSD4p
Output:
"my name is Nikki. My number is 333"
"my name is Nkiki. My neubmr is 333"
"The quick brown fox jumps over the lazy dog."
"The quick bowrn fox jmups over the lzay dog."
"\nLorem ipsum dolor sit amet, consectetur adipiscing elit, \nsed do eiusmod tempor incididunt ut labore et dolore magna aliqua. \nUt enim ad minim veniam, \nquis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat. \nDuis aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur. \nExcepteur sint occaecat cupidatat non proident, \nsunt in culpa qui officia deserunt mollit anim id est laborum.\n"
"\nLorem isupm dloor sit amet, csttunoecer andiipcsig elit, \nsed do emiousd tepmor idinicdnut ut lorbae et dorloe mgnaa aqilua. \nUt einm ad miinm vinaem, \nquis notursd eioattxceirn ualmlco libroas nisi ut aqiiulp ex ea cdmoomo cuanqesot. \nDius aute iurre dolor in rienreehredpt in vlptuotae vielt esse clulim drlooe eu fuagit nulla ptaaiurr. \nEepuxcter snit ocecacat citapadut non prinodet, \nsnut in cpula qui oficfia dsuenret milolt ainm id est laorbum.\n"
I am attempting to append a JSON element to an already existing array in my database. I know about jsonb_set however I can't upgrade to Postgres 9.4 as this is a groovy project and the latest postgresql version on Maven is 9.4.
I currently have a json structure like this:
"playersContainer": {
"players": [
{
"id": "1",
"name": "Nick Pocock",
"teamName": "Shire Soldiers",
"bio" : "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nulla imperdiet lorem tellus, in bibendum sem dignissim sed. Etiam eu elit sit amet lacus accumsan blandit sed ut dolor. Mauris vel dui non nisi vestibulum commodo vel id magna. Donec egestas magna in tincidunt mollis. Fusce mauris arcu, rhoncus ut lacus sed, fermentum ultrices elit. In sollicitudin at ex dapibus vestibulum. Pellentesque congue, est id lobortis viverra, mauris lectus pharetra orci, ut suscipit nisl purus vehicula est. Aliquam suscipit non velit vel feugiat. Quisque nec dictum augue.",
"ratings": [
1,
5,
6,
9
],
"assists": 17,
"manOfTheMatches": 20,
"cleanSheets": 1,
"data": [
3,
2,
3,
5,
6
],
"totalGoals": 19
}
}
I want to append new players to the player array and update my database, I tried doing an update but it wiped the rest of the data. Is there a way to target the players array and append the new json object to it?
Unfortunately 9.4 does not have json_set function. You can use something like this:
WITH old_players AS (
SELECT $1 AS j
), new_player AS (
SELECT $2 AS j
), all_players AS (
SELECT json_array_elements(j->'playersContainer'->'players') AS p
FROM old_players
UNION ALL
SELECT *
FROM new_player
) SELECT ('{"playersContainer": {"players": ' || json_agg(p) || '}}')::json
FROM all_players
;
You can use it as function:
CREATE OR REPLACE FUNCTION add_player(old_player json, new_player json) RETURNS json AS $$
WITH all_players AS (
SELECT json_array_elements(($1)->'playersContainer'->'players') AS p
UNION ALL
SELECT $2
)
SELECT ('{"playersContainer": {"players": ' || json_agg(p) || '}}')::json
FROM all_players
$$ LANGUAGE sql IMMUTABLE;
And after that you can just call it :
UPDATE site_content SET content = add_player(content, '{"id": "2", "name": "Someone Else"}') where id = :id;
I'm trying to sort an array of characters in C. My bubble sort algorithm is a standard one but when I try to print the arrays after using the sort method they appear to be empty.
Is this a problem with my pointer usage?
#include <stdio.h>
#include <string.h>
char Gstr1[256];
char Gstr2[256];
void load();
void printArrays();
void sortArray(char *array);
main()
{
load();
printArrays();
sortArray(&Gstr1[0]);
sortArray(&Gstr2[0]);
printf("\n\n");
printArrays();
}
void load()
{
memcpy (Gstr1,"Sed aliquam neque fermentum leo semper sagittis. Curabitur imperdiet, libero vulputate laoreet tristique, magna justo posuere, quis rutrum ligula tortor vitae eros. Phasellus sed dignissim elit, nec dictum ligula. Vivamus ornare ultrices odio eget dictum.",255);
memcpy (Gstr2,"Lorem ipsum dolor si amet, consectetur adipiscing elit. Aenean dapibus libero a convallis sodales. Mauris placerat nisl leo, vitae tincidunt turpis tristique in. Pellentesque vehicula nisl vitae efficitur ornare. Nunc imperdiet sem, in aliquam rhoncus at.",255);
}
void printArrays()
{
printf(Gstr1);
printf("\n\n");
printf(Gstr2);
}
void sortArray(char *array)
{
int i,j;
char temp;
for(i=0;i<(256-1);i++)
for(j=0;j<(256-i-1);j++)
{
if((int)*(array+j)>(int)*(array+(j+1)))
{
temp=*(array+j);
*(array+j)=*(array+(j+1));
*(array+(j+1))=temp;
}
}
}
This is because of the string length. The length of first string is 256 and second is 257, and you're not taking care of '\0' character. Hence, it is advisable to use memcpy_s() instead of memcpy() and also, use strlen() instead of hardcoding the array size in the for loops. However, with minor correction of the for loop limit, the following code produces the output.
Code:
#include <stdio.h>
#include <string.h>
char Gstr1[256];
char Gstr2[256];
void load();
void printArrays();
void sortArray(char *array);
main()
{
load();
printArrays();
sortArray(&Gstr1[0]);
sortArray(&Gstr2[0]);
printf("\n\n");
printArrays();
}
void load()
{
memcpy (Gstr1,"Sed aliquam neque fermentum leo semper sagittis. Curabitur imperdiet, libero vulputate laoreet tristique, magna justo posuere, quis rutrum ligula tortor vitae eros. Phasellus sed dignissim elit, nec dictum ligula. Vivamus ornare ultrices odio eget dictum.",255);
memcpy (Gstr2,"Lorem ipsum dolor si amet, consectetur adipiscing elit. Aenean dapibus libero a convallis sodales. Mauris placerat nisl leo, vitae tincidunt turpis tristique in. Pellentesque vehicula nisl vitae efficitur ornare. Nunc imperdiet sem, in aliquam rhoncus at.",255);
}
void printArrays()
{
printf(Gstr1);
printf("\n\n");
printf(Gstr2);
}
void sortArray(char *array)
{
int i,j;
char temp;
for(i=0;i<strlen(array);i++)
for(j=0;j<(strlen(array)-i-1);j++)
{
if((int)*(array+j)>(int)*(array+(j+1)))
{
temp=*(array+j);
*(array+j)=*(array+(j+1));
*(array+(j+1))=temp;
}
}
}
You sort the last character in the array as well resulting in a sorted character array with leading null terminator.
Therefore just adjust your loops to fix your issue as shown below.
Of course it would be better to pass the array size with a parameter but that's a different topic :)
void sortArray(char *array)
{
int i,j;
char temp;
for(i=0;i<(256-2);i++)
for(j=0;j<(256-i-2);j++)
{
if((int)*(array+j)>(int)*(array+(j+1)))
{
temp=*(array+j);
*(array+j)=*(array+(j+1));
*(array+(j+1))=temp;
}
}
}
I have added txtview by using this function >>
text_v = gtk_text_view_new()
bt here scroll is not working and also how to set textview size, have used this one =>>
gtk_widget_set_size_request(text_v,400,200);
bt is also not working
This is the way I did it :
#include<gtk/gtk.h>
int main(int argc, char* argv[])
{
GtkWidget *textview, *window, *scrolledwindow;
GtkTextBuffer *buffer;
gtk_init(&argc, &argv); /*void gtk_init (int *argc,char ***argv);*/
window = gtk_window_new(GTK_WINDOW_TOPLEVEL);
gchar* sample_text = "Lorem ipsum dolor sit amet, consectetur adipiscing elit,\n" \
"sed do eiusmod tempor incididunt ut labore et dolore magna\n" \
"aliqua. Ut enim ad minim veniam, quis nostrud exercitation\n" \
"ullamco laboris nisi ut aliquip ex ea commodo consequat.\n"\
"Duis aute irure dolor in reprehenderit in voluptate velit\n"\
"esse cillum dolore eu fugiat nulla pariatur. Excepteur sint\n"\
"occaecat cupidatat non proident, sunt in culpa qui officia\n"\
"deserunt mollit anim id est laborum.";
textview = gtk_text_view_new();
gtk_widget_set_size_request(textview, 400, 200); // This is but a request. The sizes are not guaranteed.
scrolledwindow = gtk_scrolled_window_new(NULL, NULL);
buffer = gtk_text_view_get_buffer(GTK_TEXT_VIEW(textview));
gtk_text_buffer_set_text(buffer, sample_text, -1);
gtk_container_add(GTK_CONTAINER(scrolledwindow), textview);
gtk_container_add(GTK_CONTAINER(window), scrolledwindow);
gtk_widget_show_all(window);
gtk_main();
return 0;
}
If you need to customize the scroll window it is worth having a look here.