CareerCup

10. differences between
char *str = "SIVA" and char str1[]="SIVA"

str is a pointer to a constant string. str1 is a constant pointer.

sub questions:
1) where string literal i.e "SIVA" will be stored ( heap , stack, data or code segments) in above both cases.
str - code segment
str1 - stack

2) char *str = "SIVA";
str[0] = 'f' ;
any error ? compile time error or run time error ?

run time error, as you trying to modify a constant string.

3) char *p = (char *) str;
p[0] = 'f' ;
any error ? compile time error or run time error ?

2) reasoning still applies here. runtime error.

1. code segment (read only)
2 & 3: Compile time error.

It depends on the compiler about where it places data.
For ex. 1. On TC, there will be no errors and everything should work fine, so we can say that str is stored in data or stack area (so it can be modified) and str1 is stored in stack area.
2. On GCC, str seems to be stored in read-only section i.e. code area and so it can be modified, whereas str1 is stored on stack. We will encounter run time errors for str as it is stored in code area.

1.data segment.
2.no error.
3.not sure

1. str is a pointer to a constant string, str1 is a constant pointer
don't know where str is stored, but str1 is stored in stack
2. run time error because we try to change a constant
3. run time error because of the same reason in 2.

In function ‘int main()’:
warning: deprecated conversion from string constant to ‘char*’

So in this case char *str = "SIVA"

if we try to modify it we will get segmentation fault

int main(){
	char *p = "We";
	char *w = p;
	w[0] = 'H';
	printf("%s", w);

	return 0;
}

2,3. Run-Time error in minGW, since we are trying to modify:
char * str = "blah"; //which is equivalent to
const char * str = "blah";

However, note that:
const char * str = "blah";//is not equivalent to
const (char *) str = "blah";

Hope it helps.