program returns invalid value for strlen

[Satya]

Hi,

i have started writing a program for palindrome checking of characters.
i have written the following program

#include <stdio.h>
int check(char *data,int len);

int main(int argc, char **argv)
{
    char array[100];
    int len=0;

    printf("Enter the string less than 100 chars\n");
    scanf("%s",array);
    len = strlen(array);
    check(array,len);
    return 0;
}

int check(char *data, int len)
{
    char array[100]; 
    int index=0;
    data += len;
    while(len--)
        array[index++] = *data--;

    printf("%s%d",array,len);
return 1;

}

i have not completed the program. But i tried to run the program i found that the len variable is -1. How the len variable is -1 it should have been the length of the string. why am i getting -1? Can someone please help me.

Thanks and regards,
satya

[Salem]

> while(len--)
What value of len causes this loop to exit?
What value will len have, when it exits the loop?

[Satya]

yeah i understood, it is copying the null character in the first byte and hence it is not printing any array. Thanks