C Programming Question

[pyro120]

I am fairly new to C as a programming language, I have a little experience with it and robotics, however I was trying to write a simple program that would take a distance(in inches) and convert it to the number of sprockets that would be counted by a hall effect sprocket counter. I am having some trouble however with how to input the integer value for inches. I tried scanf but that didnt work. What else can I try to fix this problem?

A.J.

[Hal[PT]]

You can try scanf again...

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int my_input;

...

scanf(" %d", &my_input);

No?[/code]

[pyro120]

No, I just tried a scanf again and it comes up with a runtime error. I am using lcc compiler for windows.. I havent fully switched to gentoo yet. Here is my code. There are probably a few errors in it if anyone would like to check it for me.

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#include <stdheaders.h>

int main(void){
	int inches;
	int revolutions;
	int sprockets;

	printf("Inches:");
	scanf("%d",inches);

	revolutions = inches / 25;
	sprockets = revolutions * 4;

	printf("sprockets %d",sprockets);
}

Thanks in advance.. AJ

[EzInKy]

printf("Inches:");
scanf("%d",inches);

You need to pass the address of "inches", not it's value. Look at Hal's example again.

Here is the relevant section from the Gnu C library info page:

int scanf (const char *template, ...)

The scanf function reads formatted input from the stream stdin under the control of the template string template. The optional arguments are pointers to the places which receive the resulting values.

The return value is normally the number of successful assignments. If an end-of-file condition is detected before any matches are performed, including matches against whitespace and literal characters in the template, then EOF is returned.

[bll0]

scanf versus printf:

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scanf("%d",&inches);

                versus

	printf("sprockets %d",sprockets);

[voidengineer]

You should try man scanf first! Then consider trying sscanf :)

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#include <stdheaders.h>
#define STRBUF 20 /* or whatever */
int main(void)
{
        int inches;
        int revolutions;
        int sprockets;
        char readLine[STRBUF];

        printf("Inches:");
        fgets(readLine, STRBUF*sizeof(char), stdin);
        sscanf(readLine, "%d", &inches);
   
        revolutions = inches / 25;
        sprockets = revolutions * 4;

        printf("sprockets %d", sprockets);
}

I didn't actually compile this, but it should work. Please pay your respects to the people that bring you linux, and the men that created C, and make tabstops 8 spaces please.

[bll0]

Then consider trying sscanf

sscanf is not secure because it may cause buffer underruns. I think your program might not be very security relevant, but don't get used to sscanf.
And if you really want to have a good compiler, try coding in your gentoo and run gcc, as lcc is only an adaption of it for windows.

[voidengineer]

Ok, well do what you will with your super secure code, but remember one thing. When people go blabbing about secure code and what not; remember that it's not what functions were chosen, it's how they were used.

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 ...,STRBUF*sizeof(char), ... 

rofl buffer underruns

[emil]

Please pay your respects to the people that bring you linux, and the men that created C, and make tabstops 8 spaces please.

Or just use whatever suits _you_.

[Genone]

And if you really want to have a good compiler, try coding in your gentoo and run gcc, as lcc is only an adaption of it for windows.

I think you're wrong with that statement.

[bll0]

And if you really want to have a good compiler, try coding in your gentoo and run gcc, as lcc is only an adaption of it for windows.

I think you're wrong with that statement.

Sorry, my mistake. Mixed-up accidently lcc and cygwin... So you're right.

[pyro120]

Ok.. After fixing my scanf statement everything worked fine Thanks for the help.

A.J.