Solution of Puppetting On Strings in C programming language

If we are bent upon receiving the strings from keyboard using scanf( ) and then storing their addresses in an array of pointers to strings we can do it in a slightly round about manner as shown below.

#include "alloc.h"
main( ){
char *names[6] ;
char n[50] ;
int len, i ;
char *p ;
for ( i = 0 ; i <= 5 ; i++ )
{
printf ( "\nEnter name " ) ;
scanf ( "%s", n ) ;
len = strlen ( n ) ;
p = malloc ( len + 1 ) ;
strcpy ( p, n ) ;
names[i] = p ;
}
for ( i = 0 ; i <= 5 ; i++ )
printf ( "\n%s", names[i] ) ;
}

Here we have first received a name using scanf( ) in a string n[ ]. Then we have found out its length using strlen( ) and allocated space for making a copy of this name. This memory allocation has been done using a standard library function called malloc( ). This function requires the number of bytes to be allocated and returns the base address of the chunk of memory that it allocates. The address returned by this function is always of the type void *. Hence it has been converted into char * using a feature called typecasting. Typecasting is discussed in detail in Chapter 15. The prototype of this function has been declared in the file ‘alloc.h’. Hence we have #included this file.
But why did we not use array to allocate memory? This is because with arrays we have to commit to the size of the array at the time of writing the program. Moreover, there is no way to increase or decrease the array size during execution of the program. In other words, when we use arrays static memory allocation takes place Unlike this, using malloc( ) we can allocate memory dynamically, during execution. The argument that we pass to malloc( ) can be a variable whose value can change during execution.
Once we have allocated the memory using malloc( ) we have copied the name received through the keyboard into this allocated space and finally stored the address of the allocated chunk in the appropriate element of names[ ], the array of pointers to strings.
This solution suffers in performance because we need to allocate memory and then do the copying of string for each name received through the keyboard.