Lab 7 Solution

(6 pts total) Design First (3 pts), Then Write Code (3 pts)

To help you practice functions, you will write a short program that asks the user to enter a string (​get_string​()), makes a copy of the string, takes the copy and changes all non-space letters to dashes (​set_replace_string​()). The program then gets a letter from the user to search in the original string and replace the dashes in the copy string with the letter found, returning the number of letters found (​get_search_replace​()).

You should design first. You can have more functions, but you must have at least the three below with the EXACT function prototypes.
Each of your functions​​should have the proper function headers/descriptions

void get_string(string *);

void set_replace_string(string, string *);

int get_search_replace(char, string, string &);

Write the function headers/descriptions for each of the functions above, as well as all the functions you create. This includes information about parameters, return values, and pre/post conditions.

Design – ​Give as much detail as possible for the main function and all the functions above.
    • ​Why do the function prototypes have the specific parameter types on them?

    • ​Why do the functions have void or a return value?

    • ​How do all the functions interact together?

    • ​What do you plan to use as bad values? Good values?
    • ​What do you expect to happen with bad values? Good values?



Get checked off by a TA before beginning to implement. This will help with logic and function mistakes​.

Now, incrementally write your functions and program.

(4 pts) Understand Pointers/Dynamic Memory

Write 3 different functions in C++ to create memory on the heap​without causing a memory leak. Hint: You will need to assign the address to a pointer that was created outside the function. Remember, you can return an address or change what a pointer points to (the contents of a pointer) in a function by passing the pointer by reference or by passing the address of the pointer.

What if you want to change the contents of what the pointer points to? ​Make a function that will set the contents of the space on the heap​. Do you still need to pass by reference or the address of the pointer? Why or why not?

How will you delete the memory off the heap? Try doing it outside a function, now inside a function. ​Make sure your delete function is setting your pointer back to NULL​, since it is not supposed to be pointing anywhere anymore.

You can check to see if you have any memory leaks using valgrind.

%valgrind program_exe