CODEWITHSUNDEEP
cinputbuffer
StevenU
StevenU

Reputation: 39

Input buffer to get a an input, C programming

I'm in my first steps in C programming, and I came across a task I can not find a solution to.
The task is simple: taking a character from the user.
After that, you receiving a string from the user until the user types the * character.
Then print the number of times the user typed the first character.

I was able to solve the problem using char [SIZE]ת when I placed a maximum input size of 255 bytes (#define SIZE 255).
Nevertheless, my teacher tells me that although the solution is working well, this was not the purpose of the exercise, also, I can not assume a maximum string size.

He asks us to use the input buffer.
No dynamic memory allocation is used in the exercise, and only the stdio.h library is allowed.

I read a lot about the input buffer, but I still have not found the possibility to solve the exercise - how can I absorb value from the user without knowing its size?

I would be happy to receive assistance and tips on how to use the input buffer correctly.
Or more focused, how to input values (string of characters) into the input buffer, and then go over each character separately in this string and process it.

Thank You

Upvotes: 0

Views: 2682

Answers (1)

klutt
klutt

Reputation: 31389

There is no need to store all characters. Once you have read a character you can throw it away and just increase a counter. Something like this:

#include <stdio.h>

int main() {
    char c, first;
    int counter=0;
    printf("Enter first character: ");
    scanf("%c", &first);
    do {
        scanf("%c", &c);
        if(c == first)
            counter++;
    } while (c != '*');
    printf("You entered '%c' %d times\n", first, counter);
}

Output:

Enter first character: a
aaaaa*
5

or

Enter first character: a
aabbaa*
You entered 'a' 4 times

Note:

As been pointed out in the comments, scanf is not a good tool for this kind of stuff. I would advice against the usage of it, unless you know it is the right tool. But that's beside the point. The point here was to show you that you don't need to store the whole input buffer. If you want to look at alternate input methods (as William Pursell suggested in the comments) you could have a look at fgetc, getc, or getchar for reading single characters. fread is also a tool you should get familiar with.

Upvotes: 1

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