Why did the string become immutable in this function ?

[daudiam]

I compiled the following code on gcc :

# include <stdio.h>
fun(char str[100])
{
	str[0]='c';
}
int main()
{
	fun("wah");
	return 0;
}

On running it gave Segmentation fault. On running the debugger, I found that the problem was in :

str[0]='c';

If I first take "wah" in a string variable, and then pass that variable to fun(), then there is no problem. Why is this happening ?

[cyberfish]

String literals are actually "const char *". They could be stored in areas of memory you are not allowed to modify (and it looks like the case here).

"char str[100]" in parameter list is the same as "char *str". C passes arrays as pointers (to the first element).

[daudiam]

Thanks.