Beginner needs help with C

[Benjamin]

I just started learning C and I have a question about float...

i made a simple multiplying program:

#include<stdio.h>
#include<stdlib.h>

main()
{
float x;
float y;
float answer;
char xchar;
char ychar;

printf("Enter a number:\n");
gets(xchar);
x=atoi(xchar);
printf("Enter a second number\n");
gets(ychar);
y=atoi(ychar);
answer=x*y;
printf("%f x %f = %f\n",x,y,answer);

}

When I try to muliply decimal numbers, it will give me the answer but if the answer if supose to have a decimal point, it will only give the numbers that come before the decimal. like 5.33 x 2 will equal 10 and not 10.66

[Mart]

Its because you use atoi (ascii to integer), try using atof instead.

[Benjamin]

Thanks!

[gamezfreak]

I suggest using "scanf" instead of "gets".

scanf("%s", &xchar)

scanf basically waits for the user to input the data, and once "enter" is pressed it stores the data into the variable "xchar".

printf("Enter a number: ");
scanf("%s", &xchar);

It's just personal opinion I guess, but I just prefer to use printf and scanf

[Benjamin]

What's the difference between the two methods? I just got 'gets' from a tutorial that I was reading.

[gamezfreak]

I'm not sure on the actual difference, it's just I prefer the printf and scanf method, they are easier to remember, and the format is generally the same

[killgORE]

I think that printf and scanf are better methods too... Again, personal preference. I think that they are buffered input/output streams. hence the "enter" is the newline character, and the "SUBMIT". So the I/O methods are closer to the way "proper" command line apps work i.e. telnet...

A word of advice... It is probably best to develop a 'library' of input checking functions that you can use forever. I suggest two functions.... 1) getCleanString(question) & 2) getCleanInt(question) or getCleanInt(question, start, end)

where "question" is a text question that is needed to be asked i.e. "Please enter a number (1-10)" and start = 1 and end = 10, so you can accept input only between a certain range. This way you can verify you user input always and prevent programs from crashing. Sorry. Went a bit off topic I think.

[Benjamin]

I didn't fully understand what you just said How do I use the scanf? I think I'll start using it.

[Benjamin]

Ohh wait I think I get it. %s meaning 'string' right?

[gamezfreak]

Yup scanf uses your usual printf formatting identifiers.

Printf and Scanf are useful in file I/O aswell.