C spliting strings into an array outputs just the first token - c

Question

I am writing a microshell program as homework at my university.
Everything goes well besides one function that's not doing exactly what I'd wish it did.
I am quite new to C programming, always used higher level languages.
In fact the only times I worked with C was fiddling around with Arduino.
So I've got a line of what user inputs on the prompt. I'm trying to split it into an array of strings separated by space.
I initialized an array with
char **args = NULL;
args = malloc(sizeof(char *) * LINE_LENGTH);
And I'm sending it to a function parse_line(line, args)
The function looks like this:
bool parse_line(char *line, char **arr) {
size_t i = 0;
char *point;
point = strtok(line, " ");
while (point != NULL) {
arr[i] = malloc(strlen(point) + 1);
strcpy(arr[i], point);
point = strtok(NULL, " ");
i++;
}
arr[i] = NULL;
if (!arr)
return false;
return true;
}
The thing is that afterwards in the arr resides only first token from the splitted up line.
I am debugging it and though variable 'point' gets the right values, they aren't copied into my array. Why? I don't know.
Oh.. and the line is an array of chars, dynamic one.
char * line = NULL;
line = read_input_line();
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <stdbool.h>
#include <sys/types.h>
#include <sys/wait.h>
#define LINE_LENGTH 50
void clear_screen();
void display_prompt(bool clearscr);
char * read_input_line();
void print_line(char *line);
bool parse_line(char *line, char **arr);
int main() {
bool initialRun = true;
while (true) {
// display prompt on the screen
display_prompt(initialRun);
if (initialRun)
initialRun = false;
// read input line from terminal
char * line = NULL;
line = read_input_line();
// basic commands
if (line == NULL)
continue;
if (strcmp(line, "exit") == 0) {
free(line);
exit(EXIT_SUCCESS);
} else if (strcmp(line, "clear") == 0) {
clear_screen();
continue;
}
// parse line into array
char **args = NULL;
args = malloc(sizeof(char *) * LINE_LENGTH);
if (!parse_line(line, args)) {
printf("Error during parsing command \n");
continue;
}
}
return 0;
}
void clear_screen() {
printf("\e[2J\e[H");
}
void display_prompt(bool clearscr) {
if (clearscr)
clear_screen();
printf(" > ");
}
char * read_input_line() {
char * line = (char *)malloc(sizeof(char) * LINE_LENGTH);
if (!fgets(line, LINE_LENGTH, stdin))
return NULL;
size_t len = strlen(line);
if (len > 0 && line[len-1] == '\n') {
line[--len] = '\0';
}
return line;
}
void print_line(char *line) {
printf("%s \n", line);
}
bool parse_line(char *line, char **arr) {
size_t i = 0;
char *point;
point = strtok(line, " ");
while (point != NULL) {
arr[i] = (char *)malloc(strlen(point) + 1);
strcpy(arr[i], point);
point = strtok(NULL, " ");
i++;
}
arr[i] = NULL;
for (int j=0; j<i; j++) {
printf("%s\n", arr[i]);
}
if (!arr)
return false;
return true;
}
Input:
ls -l -h

Answer 1

arr[i] = NULL;
for (int j=0; j<i; j++) {
printf("%s\n", arr[i]);
}
You are not using j as index so you send NULL to printf(). It's undefined behavior.
I propose you an example of implementation(still not the best but for a beginner that enough):
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>
#define LINE_LENGTH 50
char **parse_line(char *line, size_t *n);
int main(void) {
while (true) {
// display prompt on the screen
printf(" > ");
// read input line from terminal
char line[LINE_LENGTH];
if (!fgets(line, sizeof line, stdin)) {
return 1;
}
line[strcspn(line, "\n")] = '\0';
if (strcmp(line, "exit") == 0) {
exit(EXIT_SUCCESS);
} else if (strcmp(line, "clear") == 0) {
printf("\e[2J\e[H");
continue;
}
// parse line into array
size_t n;
char **args = parse_line(line, &n);
if (!args) {
printf("Error during parsing command \n");
continue;
}
for (size_t i = 0; i < n; i++) {
printf("%s\n", args[i]);
}
}
}
char **parse_line(char *line, size_t *n) {
char **arr = malloc(sizeof *arr);
size_t i = 0;
for (char *token = strtok(line, " "); token != NULL; token = strtok(NULL, " ")) {
char **tmp = realloc(arr, sizeof *tmp * (i + 2));
if (tmp == NULL) {
for (size_t j = 0; j < i; j++) {
free(arr[j]);
}
free(arr);
return NULL;
}
arr = tmp;
arr[i] = malloc(strlen(token) + 1);
if (arr[i] == NULL) {
for (size_t j = 0; j < i; j++) {
free(arr[j]);
}
free(arr);
return NULL;
}
strcpy(arr[i], token);
i++;
}
arr[i] = NULL;
*n = i;
return arr;
}