cin.ignore?

[learningcplusplus898]

i have to write a program that reads a sentence/1 character and will display all the characters selected in uppercase/lowercase.
problem i have is the sentence i enter gets lots into garbage or something/im not sure what happens there. and my loop counter for the characters not sure to use the ascii characters or the letters.
thanks.

#include<iostream>
#include <conio.h>
using namespace std;

void characterCount( char[100] , char );
//---------------------------------------------------------------------------
int main()
{
	char sentence[100];
	char character;
	cout<< "enter a sentence ";

	cin.get(sentence[100]);
	cin.ignore(256, '\n');

	cout<<"enter a character ";
	cin>> character;

	cout<<"your sentence was "<< sentence[100];  //this part only displays first leter from sentence.
	cout<<"\n\nyour character was "<< character << endl;

	characterCount(sentence,character);
	getch();
	return 0;
}
//---------------------------------------------------------------------------
//---------------------------------------------------------------------------
void characterCount( char words[100], char choice )
{
	int upper = 0;
	int lower = 0;

	for( int i = 0;i < '\0'; i++)
	{
			//    'A'               'Z'
		if( choice < '65' && choice > '90')
		{
			while (words[i])
			{
				choice = words[i];
				putchar (toupper(choice));
				i++;
			}
			upper + 1;
			upper++;
			cout << "you have selected " << choice << "times" << upper;
		}
				 //   'a'               'z'
		if( choice < 'a' && choice > 'z' )
		{
			lower + 1;
			lower++;
			cout << "you have selected " << choice << "times" << lower;
		}
	cout<< " " << i <<" ";
	}

	cout << "uppercase character " << choice << " "
		  << upper << " times" <<endl;

	cout << "lowercase character " << choice << " "
		  << lower << " times" << endl;

[JLBorges]

#include<iostream>
// #include <conio.h>
// using namespace std;
#include <cctype>

// void characterCount( char[100] , char );
const int SZ = 100 ;
void characterCount( const char[SZ] , char );
//---------------------------------------------------------------------------

int main()
{
    //char sentence[100];
    char sentence[SZ];
    char character;
    std::cout << "enter a sentence ";

    // cin.get(sentence[100]);
    std::cin.get( sentence, SZ ) ;
    std::cin.ignore(256, '\n');

    std::cout << "enter a character ";
    std::cin >> character;

    // cout<<"your sentence was "<< sentence[100];  //this part only displays first leter from sentence.
    std::cout << "\n\nyour sentence was '" << sentence << "'\n\n"
              << "your character was '" << character << "'\n\n" ;

    characterCount(sentence,character);
    // getch();
    std::cout << "\nenter any character to quit: " ;
    std::cin >> character ;
    // return 0; // implicit
}
//---------------------------------------------------------------------------
//---------------------------------------------------------------------------
void characterCount( const char words[SZ], char choice )
{
    if( std::isalpha(choice) )
    {
        const char lower_case_choice = std::tolower(choice) ;
        const char upper_case_choice = std::toupper(choice) ;

        int upper = 0;
        int lower = 0;

        for( int i = 0; i < SZ ; ++i )
        {
            if( words[i] == lower_case_choice ) ++lower ;
            else if( words[i] == upper_case_choice ) ++upper ;
        }

        std::cout << "upper case character '" << upper_case_choice << "' " << upper << " times\n"
                  << "lower case character '" << lower_case_choice << "' " << lower << " times\n"
                  << "                  in all " << upper + lower << " times\n" ;
    }

    else std::cout << "character '" << choice << "' is not alphabetic\n" ;
}