Get single elements from an array?

Question

I am trying to print each char in s array one at a time. The program I have printed all the letters after the defined index in the array.

The problem I am facing is after that the user inserts the phrase then it is allocated. How do you call letters from the string using pointers?

Can you use strtok to split this string, I tried setting the delim to "" got no output. In other word make it a list like a Python split().

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


int main() {
        
    char *s;
    s = malloc(1024 * sizeof(char));
    scanf("%[^\n]", s);
    s = realloc(s, strlen(s) + 1);
   
    //printf("%s \n", s);
        
    for (int i = 0 ; i <strlen(s); i++){
        printf("%s \n", &s[i]);        
    }
        
    return 0;
}

@JonathanLeffer can you please explain you for loop in detail, please — m3sfit, Dec 12 '20 at 15:25
@m3sfit You should read the documentation for functions you're using. — klutt, Dec 12 '20 at 15:28
See also [How to prevent buffer overflow in `scanf()`?](https://stackoverflow.com/q/1621394/15168). Also read POSIX [`scanf()`](https://pubs.opengroup.org/onlinepubs/9699919799/functions/scanf.html) and note the `m` modifier ('optional assignment-allocation character'). If it is available on your system (it isn't on macOS X, for example), then you could use that instead of the `malloc()` and `realloc()`. You should also read the POSIX specification for [`printf()`](https://pubs.opengroup.org/onlinepubs/9699919799/functions/printf.html). — Jonathan Leffler, Dec 12 '20 at 17:13
The loop I wrote steps through each element of the string, up to but not including the null terminator byte (avoiding the overhead of calling `strlen()` on each iteration, which an optimizer might or might not avoid), and uses the conversion specification to print a single character (plus a newline) and passes a single character, `s[i]`. The characters are already available individually by using array indexing on the string. — Jonathan Leffler, Dec 12 '20 at 17:16

score 2 · Accepted Answer · answered Dec 12 '20 at 15:27

2

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

or

printf("%c\n", *(s + i));

answered Dec 12 '20 at 15:27

vmp

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can you explain the second `printf` statement why did you write `*(s+i)` – m3sfit Dec 12 '20 at 15:29
Because `s[i] = *(s+i)` – Krishna Kanth Yenumula Dec 12 '20 at 15:30
1

They are equivalent. S has the address of the first element of the array, you sum i positions to that and then access the value that was stored in that position. – vmp Dec 12 '20 at 15:30

score 1 · Answer 2 · answered Dec 12 '20 at 15:29

1

len = strlen(s);

for (int i = 0 ; i < len; i++){
    printf("%c\n", s[i]);        
}

answered Dec 12 '20 at 15:29

anotherOne

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score 0 · Answer 3 · answered Dec 12 '20 at 15:48

0

int main() 
{
    char *s;
    s = malloc(1024 * sizeof(char));
    scanf("%[^\n]", s);
    s = realloc(s, strlen(s) + 1);
    for (int i = 0; s[i] != '\0'; i++)
    {
        printf("%c \n", s[i]);
    }
    return 0;
}

answered Dec 12 '20 at 15:48

MED LDN

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Get single elements from an array?

3 Answers3