Breaking a char array into parts based on \n

Question

this is my first question on stack and I'm beginner in c.I declared a char array a[100]={"this is a test\n2nd test}.Now I'm trying to divide this array and take the two parts before and after \n as separate strings.So I declared a 2d array ab[i][k] and used a for loop to copy the characters to ab[i]. if a[j]=='\n', I put a NULL character at the current position of ab[i][k] and increment i by 1.But for some reason, both ab[0] and ab[1] are displaying "this is a test" when I used printf to display them.Any help or suggestions would be appreciated.

int i=0; 
char a[100],ab[100][100],c;
fputs(a,stdout);
printf("%d ",strlen(a));
for(j=0;j<=strlen(a);j++,k++)
{
    if(a[j]=='\n')
    {
        ab[i][k]='\0';
        k=0;
        i++;
        continue;
    }
    ab[i][k]=a[j];
}
printf("%s\n",ab[0]);
printf("%s",ab[1]);

Answer 1

You need to set k=-1; when you find \n , since it will be incremented at the top of the loop to 0 when you continue; .

You also need to declare int j, k=0; before the loop, to get your code to compile.

---

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

int main(int argc, char const *argv[]) {
    int i=0;
    char ab[100][100];

    char a[100] = "this is a test\n2nd test";
    printf("%d \n",strlen(a));

    int j, k=0;
    for(j=0; j<=strlen(a); j++,k++) {
        if(a[j]=='\n') {
            ab[i][k]='\0';
            k=-1;
            i++;
            continue;
        }
        ab[i][k]=a[j];
    }

    printf("1: %s\n",ab[0]);
    printf("2: %s\n",ab[1]);

    return 0;
}

23
1: this is a test
2: 2nd test

Answer 2

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

int main(int argc, char const *argv[])
{
    char ar[100] = "this is a test\n2nd test\nfoobar\netc";
    char sep[10][100];

    int i=0;
    char* token = strtok(ar, "\r\n");
    while(token != NULL) { 
        sprintf(sep[i], "%s", token);
        printf("string #%02i: `%s`.\n", i, sep[i]);
        token = strtok(NULL, "\r\n");
        i++;
    }

    return 0;
}

strtok() splits a string by any of the characters passed as a delimiter (new line and carriage return, in this case) into tokens. Passing a null pointer to the function continues where it last left off. It returns a pointer to the beginning of the token,

sprintf() saves formatted data into a variable handling \0 for you, but you could also use memcpy() or strcpy() if you like.