need to count individual letters in input

hi there, i'm new to c and I've been trying for a while now to achieve the following task, I'm hoping someone here might be able to help me out. Ok, so my program firstly allows the user to enter a string, now I need figure out how to count the different letters and numbers that are in that string. for example, if the user entered "Hello", then my program should print out the letters that are in that string, ie. e, h, l, o. My program should also print out how many times each of those letters are present, so in the case of "Hello", the program should end up printing out e - 1, h - 1, l - 2, o - 1

any help here would be much appreciated. I've been trying to use switch/case statements but still haven't managed to accomplish the task.

There are a few ways to do this. You can...

Loop through the string, and as you encounter a character, increment the approptriate variable as you encounter that character. IE: Use an array big enough to hold every character, start their count all at zero, and every time you find one, increment that spot.

Loop through the string, take a character as you encounter it, and count every occurance of that character in the string. Repeat until finished.

One takes more overhead as far as memory goes; the other takes more loops through the string.

I'm sure there are other interesting variants, but those are probably the two most common.


Quzah.

the only problem with the second way is it would probably output each char that is in the string multiple times, multiple times. lol for example, input Hello ; output H - 1, e - 1, l - 2, l - 2, o - 1
you could always store each char in a string and as you go through the input, check to see if the letter your at has been processed already..
any other ways you can think of?

The problem perhaps with the way you are implementing it. Not the way I implement it.


Quzah.

I was thinking maybe we should sort the string first, or rather sort the individual characters in the string. For example, "Hello" becomes "eHllo". Now that the string is in order it's just that you need to match a character and count. If the match fails, count the current character and try to match it with the next one until you reach the NUL terminator.

Sorting would work nicely too. I hadn't thought of that. That's a nice one.


Quzah.

ok here's my next dilemma, when i want to check the characters I want "A" to be equivalent to "a" so basically if I input "Aa" it should print out A - 2.

Is there any methods that can convert strings to lower or uppercase?

tolower perhaps? There are many functions in <ctype.h> that preform similar tasks.


Quzah.

sweeeeet im finally making some progress, ok so i've managed to print the letters once and provide a count for each letter. the next thing I'm trying to achieve is to distinguish between numbers, letters and punctuation. are there any methods that will allow me to determine if a character is a number or not? the way i figure my program should work is to test if the character is a number or letter. if it's neither then i can just count it as being punctuation. thanks for all the help so far :)

Look up the functions in <ctype.h> as mentioned.


Quzah.

you can use isdigit() function if I am not wrong it should be included in <ctype.h> as quzah said above.

Code:

---

//Example reads in a character and checks to see if it is a digit
#include <cctype>
#include <iostream>

using namespace std;

int main()
{
    char a_char;
    cin>>a_char;
    if(isdigit(a_char))
    {
        cout<<"Is a digit!";
    }
    else
    {
        cout<<"Is not a digit!";
    }
}

---

here is your function I mentioned about, maybe you can modiyf it to use most efficiently with you program.

Quote:

---

Originally Posted by mass

you can use isdigit() function if I am not wrong it should be included in <ctype.h> as quzah said above.

Code:

---

//Example reads in a character and checks to see if it is a digit
#include <cctype>
#include <iostream>

using namespace std;

int main()
{
    char a_char;
    cin>>a_char;
    if(isdigit(a_char))
    {
        cout<<"Is a digit!";
    }
    else
    {
        cout<<"Is not a digit!";
    }
}

---

here is your function I mentioned about, maybe you can modiyf it to use most efficiently with you program.

---

Try to post C code on the C board.

the code is taken from this site and the link is,
http://www.cprogramming.com/fod/isdigit.html
If youre talking about cin>> and cout>> I just wanted to show the function did not look if its written in C or not. thanks