How to copy a string into a dynamical two-dimensional array? [closed] - c

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I have to copy the resulting strings from the streaming input to the strings of my two-dimensional array. Is it possible to do this at all and what is wrong in my code?
The task is to getchar() strings and put them in two-dimensional array
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int main()
{
char *arr = NULL;
char string[50];
char sym;
int counter = 0;
int counter_str = 0;
int i = 0;
while((sym = getchar()) != EOF)
{
if((sym != ' ') && (sym != ('\t') && (sym != '\n'))){
string[counter] = sym;
counter += 1;
}
if(sym == '\n'){
string[counter] = sym;
counter += 1;
counter_str += 1;
string[counter] = '\0';
arr = (char*) realloc(arr, counter_str * sizeof(char));
arr[counter_str - 1] = malloc(1 + strlen(string));
strcpy(arr[counter_str - 1], string);
counter = 0;
}
}
}

Answer 1

char *arr is a pointer to a char and not the 2d array you had in mind.
getchar() returns an int and EOF is usually defined as -1. It is implementation defined if char is signed or unsigned.
#define _XOPEN_SOURCE 500
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define STR_LEN 50
int main() {
char **arr = NULL;
char string[STR_LEN];
int counter = 0;
int counter_str = 0;
for(; counter + 1 < STR_LEN;) {
int sym = getchar();
if(sym == EOF)
break;
if(sym != ' ' && sym != '\t')
string[counter++] = sym;
if(sym == '\n') {
string[counter] = '\0';
char **tmp = realloc(arr, (counter_str + 1) * sizeof(*arr));
if(!tmp) {
printf("realloc failed\n");
return 1;
}
arr = tmp;
arr[counter_str] = strdup(string);
if(!arr[counter_str]) {
printf("strdup failed\n");
return 1;
}
counter = 0;
counter_str++;
}
}
for(int i = 0; i < counter_str; i++) {
printf("%s", arr[i]);
free(arr[i]);
}
free(arr);
}
and example run:
hello world
again
helloworld
again
Unless you are super concerned about fitting as many non-space and non-tab characters it might be clearer to just read then strip the string:
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define STR_LEN 50
void strip(char *s, const char *accept) {
for(;;) {
s = strpbrk(s, accept);
if(!s)
break;
*s = s[1];
}
}
int main(void) {
char **arr = NULL;
for(size_t i = 0;; i++) {
char **tmp = realloc(arr, (i + 1) * sizeof(*arr));
if(!tmp) {
printf("realloc failed\n");
return 1;
}
arr = tmp;
arr[i] = malloc(STR_LEN);
if(!arr[i]) {
printf("malloc failed\n");
return 1;
}
if(!fgets(arr[i], STR_LEN, stdin)) {
free(arr[i]);
arr[i] = NULL;
break;
}
strip(arr[i], " \t");
}
for(size_t i = 0; arr[i]; i++) {
printf("%s", arr[i]);
free(arr[i]);
}
free(arr);
}
Especially if you can bound the number of strings (N):
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define N 3
#define STR_LEN 50
void strip(char *s, const char *accept) {
for(;;) {
s = strpbrk(s, accept);
if(!s)
break;
*s = s[1];
}
}
int main(void) {
char arr[N][STR_LEN];
for(size_t i = 0; i < N; i++) {
if(!fgets(arr[i], STR_LEN, stdin))
break;
strip(arr[i], " \t");
}
for(size_t i = 0; *arr[i]; i++) {
printf("%s", arr[i]);
}
}