C$++$ Ch $7,8$ Pointers and Streams $-$

Write a program in which you create four functions that work with C$-$style strings. These functions must use pointers in their implementation and must not use any C$++$ library code.

The functions to implement are:

length $-$ which determines how many characters are in the string; its parameter is a pointer to the C$-$style string;

its output value is a number representing the count of characters in the string which might be zero$$note that the input string is not modified

indexof $-$ which determines the index location of a character; its parameters are a pointer to the C$-$style string and a character which is to be searched for; its output value is a number representing the first $($lowest$)$ index of the character or $-1$ if the character is not found in the string$$note that the input string is not modified

replace $-$ which changes every occurrences of a character within the string with a different character; its parameters are a pointer to the C$-$style string, a character representing the character to replace, and another character representing the character that each found occurrence is changed to; the output value is a pointer to the input string $($which permits easier coding for the client code$)$note that the input string is modified

concat $-$ which produces a new C$-$style string being the concatenation of two input strings; its parameters are two pointers to strings; the output value is a pointer to a newly created string which is a copy of the first string followed by a copy of the second$$note that the input strings are not modified and that the client code should delete the new string before exiting the program

Write a program that tests each function and displays the results of their use.