Convert character to lower and upper case in c++ - c++

Question

How can I compare character regardless of its case. Means suppose I enter Z if my if condition shall return true for both Z and z, character can be any alphabet from A-Z or a-z.
Like ABCbabcAABC
If I enter B then it I must get 4 as output because there are 4 B in string.
I am learning C++ on Turbo C++. I am trying to do but now not getting way out.
void main()
{
clrscr();
char str[50],ch;
char str1[50];
int i = 0, l;
cout << "Enter strings: ";
gets(str);
cout << "Enter charcter: ";
cin >> ch;
l = strlen(str);
for(i = 0; i <= l; i++)
{
cout << isupper(str[i]) ? tolower(str[i]) : toupper(str[i]);
}
puts(str);
getch();
}

Answer 1

void main()
{
clrscr();
char str[50],ch;
char str1[50];
int i=0,l;
cout<<"Enter strings: ";
gets(str);
cout<<"Enter charcter: ";
cin>>ch;
l=strlen(str);
int result=0;
for(i=0;i<l;i++)
{
if(tolower(ch)== tolower(str[i]))
{
result++;
}
}
puts(str);
puts(result);
getch();
}

Answer 2

if (tolower(str[i]) == tolower(ch)) {
cout << (isupper(str[i]) ? tolower(str[i]) : toupper(str[i]));
} else {
cout << str[i];
}
40000 is the isupper output. Non zero for an upcase char, zero for lowercase, as written in manual

Answer 3

All you need to do is to play around with the ASCII value.
Check out the code: which explains that you need to convert only those characters whoce ASCII value is between 65(A) to 90(Z).
public class Ques2 {
/**
* #param args the command line arguments
*/
public static void main(String[] args) throws IOException {
//ascii A=65 Z=90 a=97
System.out.println("Enter UPPERCASE");
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
// String input = br.readLine().toLowerCase();
char c;
char[] word=br.readLine().toCharArray();
for(int i :word)
{
if(i>=65 && i<=90){
i=i+32 ;
c=(char) i;
System.out.println(c);
}
else{
c=(char)i;
System.out.println(c);
}
}
}
}