Page 71 - DCAP201_FUNDAMENTALS_OF_DATA_STRUCTURES

Fundamentals of Data Structures

Notes An equivalent declaration is : int strlen(char *s); since char s[] ≡ char *s.
strlen() is a standard library function that returns the length of a string. Let’s look at how we may
write a function:
int strlen(char *s)
{ char *p = s;

while (*p != ‘\0);
p++;
return p-s;
}
Now lets write a function to copy a string to another string. strcpy() is a standard library
function that does this.
void strcpy(char *s, char *t)
{ while ( (*s++ = *t++) != ‘\0);}
This uses pointers and assignment by value.

Self Assessment

Fill in the blanks:

1. A ..................... is a variable which contains the address in memory of another variable.
2. The ..................... operator * gives the “contents of an object pointed to by a pointer”.
3. When we increment a pointer we increase the pointer by one “..................... ” memory.
4. When an array is passed to a function what is actually passed is its initial elements location
in ..................... .
5. ..................... is a standard library function that returns the length of a string.

5.2 Arrays of Pointers

We can have arrays of pointers since pointers are variables.
An array of pointers can be declared as :
<type> *<name>[<number-of-elements];

Example:
char *ptr[3];

The above line declares an array of three character pointers.

!
Caution Text can’t be moved or compared in a single operation.
Arrays of Pointers are a data representation that will cope efficiently and conveniently with
variable length text lines.

64 LOVELY PROFESSIONAL UNIVERSITY