Malloc function

For the prelab assignment and the lab next week use malloc function to allocate space (to store the string)

instead of creating fixed size character array. malloc function allows user to allocate memory (instead of

compiler doing it by default) and this gives more control to the user and efficient allocation of the

memory space.

Example

int *ptr

ptr=malloc(sizeof(int)*10);

In the example above integer pointer ptr is allocated a space of 10 blocks this is same as creating as array

int ptr[10] but here malloc function is used which allows the user to decide how much memory is

required.

Another example

char* string;

string = malloc(sizeof(char) * 15); //has room for 15 characters

Not even declaring the array is required, everything

must

be pointers.

Implement following functions for the pre-lab.

Description:

Implement following functions for the prelab assignment. These will be on the lab!

int main():

Declares a new string (char pointer), then calls getString and prints the string with

the size out and frees the malloced memory from the string.

int getString(char *):

This function takes in an uninitialized string, prompts the user for the size

of the string (error checking to make sure size is between 1-20), and then prompts and scans in

the actual string from the user and converts it to upper case. Returns the size of the string, and

the string should be valid when the function terminates (hint: if the user enters in a string length

less than the size but not empty, adjust the size. Using getSafeString from hw2 might be a good idea).

int checkString(char*, int):

Takes in the string and the size, and checks to see if the string is

valid. Valid string should contain

only alphabetical characters A through Z, not including the null

terminator. Return 1 if string is valid, otherwise 0 if string is invalid. (hint: try using the acsii values

instead of checking for specific characters)

Sample output:

Enter the size of the string:

109

Please enter again:

-1

Please enter again:

7

Please enter the string:

0

Please enter a valid string:

stringstringstring

The string entered is longer than the allowed size

Please enter a valid string:

89994

Please enter a valid string:

5tring5

Please enter a valid string:

String

You entered: STRING which is size 6

./a.out

Enter the size of the string:

0

Please enter again:

18

Please enter the string:

&#^I$@OI$

Please enter a valid string:

baseball bat

Please enter a valid string:

baseball

You entered: BASEBALL which is size 8

Note:

1. Dont use any global variables, though a global constant for the maxsize of string (20) is ok.

2.

Use only pointer notation and pointer arithmetic to implement the assignment.

3. Use the relevant library function, especially from ctype.h

Library function youll need to free the string at the end:

https://www.tutorialspoint.com/c_standard_library/c_function_free.htm

Remember that the string is passed by reference to the function: changing its contents in the function

changes it in main as well, including mallocing space for it.

Ascii table:

http://www.asciitable.com/