remove element from pointer array in C - c

Question

I'm trying to figure out why I cannot delete elements from the dict array. Could somebody help me out? The function removeWord is working as it is supposed to when removing the last added word, but not when trying to remove some other word.
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAX_NUMBER_OF_WORDS 11
int clear(){
while(getchar()^'\n');
return 0;
}
int numberOfWordsInDict(char **dict){
int i = 0;
int c1 = 0;
for (i = 0; i < MAX_NUMBER_OF_WORDS; ++i){
if (dict[i] != 0){
c1++;
}
}
return c1;
}
void addWord(char **dict, char *word){
int c1 = numberOfWordsInDict(dict);
char *word1;
if (c1 >= 0 && c1 < 10){
word1 = (char*) malloc(sizeof(char)*(strlen(word)+1));
dict[c1] = word1;
strncpy(dict[c1], word, strlen(word));
dict[c1][strlen(word)] = '\0';
} else if (c1 >= 10){
printf("Dictionary is already full!\n");
}
}
void printDict(char **dict){
int i = 0;
int c1 = numberOfWordsInDict(dict);
printf("Dictionary:\n");
if (c1 == 0){
printf("The dictionary is empty.\n");
} else if (c1 > 0 && c1 <= 10){
while (dict[i] != NULL){
printf("- %s\n", dict[i]);
i++;
}
}
}
void removeWord(char **dict, char *word){
int i = 0;
for (i = 0; i < MAX_NUMBER_OF_WORDS; i++){
if (strncmp(dict[i], word, strlen(word)+1) == 0){
dict[i] = 0;// can only delete the last element of dict properly.
break;
}
}
}
int main(){
char *dict[MAX_NUMBER_OF_WORDS] = {};
char word[1024] = {};
char command;
while(1){
printf("Command (a/p/r/q): ");
while(scanf("%s", &command) == 1){
break;
}
;
clear();
if (command == 'a'){ // add word
scanf("%[^\n]s", &word);
clear();
addWord(dict, word);
} else if (command == 'p'){ // print dict
printDict(dict);
} else if (command == 'r'){ // remove word
printf("Remove a word: ");
scanf("%[^\n]s", &word);
clear();
removeWord(dict, word);
} else if (command == 'q'){ // quit
break;
}
}
int i = 0;
for (i = 0; i < MAX_NUMBER_OF_WORDS; i++){
free(dict[i]);
}
return 0;
}
example input:
a
dog
a
cat
a
apple
case 1:
r
apple
p
// output =
Dictionary:
- dog
- cat
a
uniform
p
// output =
Dictionary:
- dog
- cat
- uniform
// works fine
case 2
r
cat
p
// output =
Dictionary:
- dog
a
book
p
// output =
Dictionary:
- dog
// doesn't work as expected

Answer 1

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define MAX_NUMBER_OF_WORDS 11
int clear(){
while(getchar()^'\n');
return 0;
}
int numberOfWordsInDict(char **dict){
int c1 = 0;
for(int i = 0; i < MAX_NUMBER_OF_WORDS; ++i){
if (dict[i] != 0){
c1++;
}
}
return c1;
}
int vacancy(char **dict){
for(int i = 0; i < MAX_NUMBER_OF_WORDS; ++i){
if (dict[i] == 0){
return i;
}
}
return -1;
}
void addWord(char **dict, char *word){
int c1 = vacancy(dict);//It is not possible to use the registration number as an additional index.
if (-1 != c1){
dict[c1] = malloc(strlen(word)+1);
strcpy(dict[c1], word);
} else {
printf("Dictionary is already full!\n");
}
}
void printDict(char **dict){
int c1 = numberOfWordsInDict(dict);
printf("Dictionary:\n");
if (c1 == 0){
printf("The dictionary is empty.\n");
} else {
for(int i = 0; i < MAX_NUMBER_OF_WORDS; ++i){
if(dict[i])
printf("- %s\n", dict[i]);
}
}
}
void removeWord(char **dict, char *word){
for(int i = 0; i < MAX_NUMBER_OF_WORDS; i++){
if (strcmp(dict[i], word) == 0){
free(dict[i]);//need free
dict[i] = 0;// can only delete the last element of dict properly.
break;
}
}
}
int main(){
char *dict[MAX_NUMBER_OF_WORDS] = { NULL };
char word[1024] = { 0 };//forbids empty initializer braces
char command;
while(1){
printf("Command (a/p/r/q): ");
scanf("%c", &command);//%s buffer over run
clear();
if (command == 'a'){ // add word
scanf("%[^\n]", word);
clear();
addWord(dict, word);
} else if (command == 'p'){ // print dict
printDict(dict);
} else if (command == 'r'){ // remove word
printf("Remove a word: ");
scanf("%[^\n]", word);
clear();
removeWord(dict, word);
} else if (command == 'q'){ // quit
break;
}
}
int i = 0;
for (i = 0; i < MAX_NUMBER_OF_WORDS; i++){
free(dict[i]);
}
return 0;
}

Answer 2

Inside printDict() use
while (i<MAX_NUMBER_OF_WORDS){
if(dict[i] != 0)
printf("- %s\n", dict[i]);
i++;
}
instead of
while (dict[i] != NULL){
printf("- %s\n", dict[i]);
i++;
}
because even if you know if there are c1 number of words, you don't know their location as in where those c1 words are present.
Also change
while(scanf("%s", &command) == 1)
to
while(scanf("%c", &command) == 1)
since command is of char type.