In the below code the last call to myprint does not work (gives a
segmentation error).

But I thought that pointer variables local in main (or any other
function) would first be deleted when the calling function returns. Why
does it give a segmentation fault?

#include
#include

void myprint(double* a) {
printf("number is = %%f\n",*a);

}

int main() {

/* Working! (static allocation) */
double d1 = 1.1;
myprint(&d1);

/* Working! (dynamic allocation) */
double* d2 = (double*) malloc(sizeof(double*));
*d2 = 2.2;
myprint(d2);

How do I find the length of strings within an array at compile time?

The following is not safe:

const char* MyStrings[] =
{
"one",
"two",
"three",
"end marker"
}

#define StringLength(index) MyStrings[index+1] - MyStrings[index]

Since the strings may not be placed consecutively, or in order, within
memory.

Also

#define String1 "one"
#define String2 "two"
#define String3 "three"