Counting an inputted letter in an inputted string using getchar()

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Counting an inputted letter in an inputted string using getchar()

Oct 16th, 2007

I need to make the program:

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Write a program to ask for a string and a single character. Read in the string using getchar(). Read in the character using scanf(). Count and report the number of occurrences of the character in the string. Add a brief comment at the beginning of the file describing what the program does.

An interactive session with the program should look like (note the space at the end of the prompts, that the string appears on a separate line, indented and quoted, and that the character is printed within single quotes; sample user input is in red):

Enter any string: I could have entered anything, but this is what I typed.

Enter any character: t

In the following string:

"I could have entered anything, but this is what I typed."

The character 't' appears 6 times

This is what I got so far, but I'm completely stuck now because I keep getting errors:

 Help with Code Tags 
 cplusplus Syntax (Toggle Plain Text) 
#include <stdio.h>
#include <string.h>
 
 
int main (int argc, char**argv)
{
	int i;
	int letterCount;
	char LetterToMatch[1];
	char string[220];
 
	letterCount = 0;
	for(i = 0; i < strlen(string); i++)
	{
		if (string[i] = getchar[LetterToMatch])
			letterCount++;
 
		if (string[i] == '\n')
			{
				break;
			}
	}
 
 
	printf("Enter any string: ");
	scanf (" %s", &string);
	printf("Enter any character: ");
	scanf (" %s", &LetterToMatch);
	printf("In the following string:\n");
	printf("  \"%s\"\n", string);
	printf("The character '%c" appears %d time%s\n", 
		LetterToMatch, letterCount, letterCount == 1 ?"":"s");
 
	return(0);
}
 
#include <stdio.h>
#include <string.h>


int main (int argc, char**argv)
{
	int i;
	int letterCount;
	char LetterToMatch[1];
	char string[220];

	letterCount = 0;
	for(i = 0; i < strlen(string); i++)
	{
		if (string[i] = getchar[LetterToMatch])
			letterCount++;
	
		if (string[i] == '\n')
			{
				break;
			}
	}


	printf("Enter any string: ");
	scanf (" %s", &string);
	printf("Enter any character: ");
	scanf (" %s", &LetterToMatch);
	printf("In the following string:\n");
	printf("  \"%s\"\n", string);
	printf("The character '%c" appears %d time%s\n", 
		LetterToMatch, letterCount, letterCount == 1 ?"":"s");

	return(0);
}

I'm not even positive I have the right syntax, but here are the errors I'm getting for this code:

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15:subscripted value is neither array nor pointer
26: warning: char format, different type arg (arg 2)
28: warning: char format, different type arg (arg 2)
31: parse error before "appears"
31: stray '\' in program
31:55: warning: multi-line string literals are deprecated
32:54: warning: multi-line string literals are deprecated
32:54: missing terminating " character
31:55: possible start of unterminated string literal

Please keep in mind that I am a beginner so please try and explain in a way a beginner would understand. Thanks!

Last edited by Ancient Dragon : Oct 16th, 2007 at 7:41 am. Reason: add line numbers

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Re: Counting an inputted letter in an inputted string using getchar()

Oct 16th, 2007

getchar uses round parentheses not square brackets to hold the parameters.

you don't need the & address operator on line 26 because arrays are ALWAYS passed by address.

line 28 has a couple problems: if you only want one character then use "%c" instead of "%s". and it has the same problem as above on line 26.

line 31: The double quote immediately after '%c should be a single quote. The rest of the errors will be fixed too when you correct that.

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Re: Counting an inputted letter in an inputted string using getchar()

Oct 16th, 2007

I fixed those things, but I'm still getting errors:

 Help with Code Tags 
 c Syntax (Toggle Plain Text) 
#include <stdio.h>
#include <string.h>
 
 
int main (int argc, char**argv)
{
	int i;
	int letterCount;
	char LetterToMatch[1];
	char string[220];
 
	letterCount = 0;
	for(i = 0; i < strlen(string); i++)
	{
		if (string[i] = getchar(LetterToMatch))
			letterCount++;
 
		if (string[i] == '\n')
			{
				break;
			}
	}
 
 
	printf("Enter any string: ");
	scanf (" %c", &string);
	printf("Enter any character: ");
	scanf (" %c", &LetterToMatch);
	printf("In the following string:\n");
	printf("  \"%s\"\n", string);
	printf("The character '%c' appears %d time%s\n", 
		LetterToMatch, letterCount, letterCount == 1 ?"":"s");
 
	return(0);
}
#include <stdio.h>
#include <string.h>


int main (int argc, char**argv)
{
	int i;
	int letterCount;
	char LetterToMatch[1];
	char string[220];

	letterCount = 0;
	for(i = 0; i < strlen(string); i++)
	{
		if (string[i] = getchar(LetterToMatch))
			letterCount++;
	
		if (string[i] == '\n')
			{
				break;
			}
	}


	printf("Enter any string: ");
	scanf (" %c", &string);
	printf("Enter any character: ");
	scanf (" %c", &LetterToMatch);
	printf("In the following string:\n");
	printf("  \"%s\"\n", string);
	printf("The character '%c' appears %d time%s\n", 
		LetterToMatch, letterCount, letterCount == 1 ?"":"s");

	return(0);
}

The errors I'm getting:

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15:54: macro "getchar" passed 1 arguments, but takes just 0
In function 'main':
15: warning: assignment makes integer from pointer without cast
15: warning: suggest parentheses around assignment used as truth value
26: warning: char format, different type arg (arg 2)
28: warning: char format, different type arg (arg 2)
32: warning: int format, pointer arg (arg 2)
literal

Last edited by Exsiss : Oct 16th, 2007 at 10:44 am.

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Re: Counting an inputted letter in an inputted string using getchar()

Oct 16th, 2007

what have YOU tried to fix the problems? Look at the error messages, they tell you what lines are incorrect. Then look up the function in your textbook or online and see why the compiler says you are wrong.

line 13 is wrong -- what is the value of string when it first enters that loop ? Hint: its value is just some random junk because you didn't initialize it to anything. And even if you did initialize it that line would still be wrong.

Last edited by Ancient Dragon : Oct 16th, 2007 at 10:51 am.

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Re: Counting an inputted letter in an inputted string using getchar()

Oct 16th, 2007

Thanks for the help on line 13. I guess I need to look up initializing strings some more and understand it a little better.

I see the errors, I just don't know what they mean. For instance does "char format, different type arg" always mean the letter that comes after "%" (same with int format)? and I don't even know what a truth value or a cast is. and "15:54: macro "getchar" passed 1 arguments, but takes just 0" I don't even understand at all.

And they are not things I can find in my book or online (because I don't even know what to be searching for).

Last edited by Exsiss : Oct 16th, 2007 at 11:18 am.

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Re: Counting an inputted letter in an inputted string using getchar()

Oct 16th, 2007

Why is LetterToMatch defined as an array of one char? Why not just define it as a char and it won't be a pointer, correcting some of the errors.

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Re: Counting an inputted letter in an inputted string using getchar()

Oct 16th, 2007

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Originally Posted by WaltP

Why is LetterToMatch defined as an array of one char? Why not just define it as a char and it won't be a pointer, correcting some of the errors.

Do you mean making line 9 "char LetterToMatch[];" instead of "char LetterToMatch[1]"?

Because when I do that it says I have an array size missing in "LetterToMatch".

Sorry if this all sounds stupid, I'm having trouble grasping the C language.

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Re: Counting an inputted letter in an inputted string using getchar()

Oct 16th, 2007

Okay, I don't know if it was a very good mistake or if something clicked in my brain but I was able to figure something out, my code is now:

 Help with Code Tags 
 c Syntax (Toggle Plain Text) 
#include <stdio.h>
#include <string.h>
 
 
int main (int argc, char**argv)
{
	int i;
	int letterCount;
	char LetterToMatch;
	char string[30];
 
	letterCount = 0;
	while ( (i = getchar() ) != EOF)
	{
		if (  i >= 'LetterToMatch')
			letterCount++; 
	}
 
 
	printf("Enter any string: ");
	scanf (" %c", string);
	printf("Enter any character: ");
	scanf (" %c", &LetterToMatch);
	printf("In the following string:\n");
	printf("  \"%s\"\n", string);
	printf("The character '%c' appears %d time%s\n", 
		LetterToMatch, letterCount, letterCount == 1 ?"":"s");
 
	return(0);
}
 
#include <stdio.h>
#include <string.h>


int main (int argc, char**argv)
{
	int i;
	int letterCount;
	char LetterToMatch;
	char string[30];

	letterCount = 0;
	while ( (i = getchar() ) != EOF)
	{
		if (  i >= 'LetterToMatch')
			letterCount++; 
	}


	printf("Enter any string: ");
	scanf (" %c", string);
	printf("Enter any character: ");
	scanf (" %c", &LetterToMatch);
	printf("In the following string:\n");
	printf("  \"%s\"\n", string);
	printf("The character '%c' appears %d time%s\n", 
		LetterToMatch, letterCount, letterCount == 1 ?"":"s");

	return(0);
}

And now the only error I have is

[quote}
15:28: warning: character constant too long
[/quote]

what does it mean when it says '15:28:'? Is it still referring to lines? And can someone tell me what "character constant too long" means?

Also, the 'while ( (i = getchar() ) != EOF)' I got from the book. does anyone know what EOF is supposed mean?

Also, I tried running the program anyway and when I did a blank line was given where I can type and send, but nothing happens and I can't get out of it.

Thanks

Last edited by Exsiss : Oct 16th, 2007 at 3:15 pm.

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Re: Counting an inputted letter in an inputted string using getchar()

Oct 16th, 2007

>if ( i >= 'LetterToMatch')
I'm going to go out on a limb and guess that you meant:

Help with Code Tags

(Toggle Plain Text)

if ( i == LetterToMatch )

LetterToMatch is a variable, and you're checking to see if i matches it, correct? Also, if you're going to test against LetterToMatch, you need to make sure that it's actually been set to something.

>does anyone know what EOF is supposed mean?
It's supposed to mean end-of-file, or "you've reached the end of the data".

Last edited by Narue : Oct 16th, 2007 at 3:16 pm.

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Re: Counting an inputted letter in an inputted string using getchar()

#10

Oct 16th, 2007

Thank you Narue, you have been extremely helpful! I fixed the if statement and it changed my error to '22:28:' instead of '15:28:' so it must have done something (although i don't know what haha).

>if you'r going to test against LetterToMatch, you need to make sure that it's actually been set to something.
I'm guessing that because you said this that LetterToMatch is not set to anything? I'm so confused, I know how to do this code without the scanf() but not knowing what the letter is is throwing me off.

Should I have a #define LetterToMatch at the beginning?

Another thing I'm having trouble grasping is what exactly (i = getchar() ) is telling the program (again, I'm having troubles understanding getchar, this might be due to the fact I've been up practically all night trying to figure these programs out, :/). Maybe if I understand what (i = getchar() ) is doing I will understand this a little better. (namely I'm confused to what i is even representing...)

Also, do you think I need the '!= EOF' in line 20?

Sorry about all the questions, this is just really frustrating me.

Edit: I also just changed line 22 to "if ( string[i] == 'LetterToMatch')" and I tried running the program anyway and when I did it did ask me to enter any string, but then when I did and sent it it said "Enter any character: In the following screen:" and then went down a new line and is just blank, and I can type anything, but it won't do anything, and it won't let me out of the program.

Last edited by Exsiss : Oct 16th, 2007 at 3:41 pm.