使用指针从2D数组打印字符串

Question

I am trying to build a program that uses dynamic allocation to build an array of strings. After the user finishes to enter the words he wants into the array i want to print the array one word after the other. I am using pointers to pointers, however it doesn't seem to work:

#define SIZE 256
void paintWords(char **words, int count_words);

void main() {
    char **words = NULL;
    int flag = 1;
    char buffer[SIZE];
    int count_words = 0;
    char *curr_word;
    while (flag)
    {
        _flushall();
        printf("Enter a word:");
        gets(buffer);
        words = (char**)realloc(words,++count_words*sizeof(char*));
        curr_word = (char*)malloc(strlen(buffer) + 1);
        words[count_words - 1] = curr_word;
        printf("Do you wish to continue(0-no, 1-yes):");
        scanf("%d", &flag);
    }
    paintWords(words, count_words);
}

void paintWords(char **words, int count_words) {
    int j = 0;
    for (int i = 0; i < count_words; i++)
    {
        printf("%s\n", words[i][j]);
    }
}

Answer 1

1. Copy buffer to your malloc 'ed block with strcpy

    strcpy(curr_word, buffer); 

   you are discarding the read word since you don't put it anywhere

2. Don't use gets use fgets instead

    fgets(buffer, sizeof(buffer), stdin); 

   this would prevent a buffer overflow.

3. This is just the j st which in your case is the 0 th character of the word

    printf("%s\\n", words[i][j]); 

   change it to

    printf("%s\\n", words[i]); 

   turn compiler warnings on, it would tell you about printf expecting a char * and recieving char instead.

Also consider the following:

1. main() should return int .
2. You don't need to cast malloc .
3. Don't overwrite your pointer with realloc , use a temporary pointer and assign it to array on success only. Otherwise if realloc returns NULL you will not be able to free(array) for example.

Answer 2

++count_words
words = realloc(words,count_words*sizeof(char*));
words[count_words-1] = malloc(strlen(buffer) + 1);

strcpy(words[count_words-1],buffer);

Later print the array

printf("%s\n",words[i]);

realloc() can fail so

char *temp = realloc(words,count_words*sizeof(char*));

if(temp != NULL)
words = temp;

Few other fixes will be

You shouldn't be using gets which is no more a standard. Use fgets() and note that fgets() comes with a newline character

Check the code below:

#include<stdio.h>
#include<stdlib.h>
#include<string.h>

#define SIZE 256
void paintWords(char **words, int count_words);

void main() {
    char **words = NULL,ch;
    int flag = 1;
    char buffer[SIZE];
    int count_words = 0;
    //char *curr_word;
    while (flag)
    {

        printf("Enter a word:");
        fgets(buffer,sizeof(buffer),stdin);

        words = (char**)realloc(words,++count_words*sizeof(char*));

        words[count_words - 1] = (char*)malloc(strlen(buffer) + 1);
        strcpy(words[count_words-1],buffer);
        printf("Do you wish to continue(0-no, 1-yes):");
        scanf("%d", &flag);
        while((ch = getchar()) != '\n');
    }
    paintWords(words, count_words);
}

void paintWords(char **words, int count_words) {
    int i;
    for (i=0; i < count_words; i++)
    {
        printf("%s", words[i]);
    }
}