upper to lowercase

[Tom Brown]

how can i fix this error
[code]
int count=0;
char str[]=respond;
char c;
while (str[count])
{
c=str[count];
putchar(tolower(c));
count++;
}
[code]
well i'm writing a program and i use the word respond to store the string and i declared it but i keep getting error why?

[DDomjosa]

char str[] = "respond";