What is wrong with division?

[nerio]

Hi.

I study C. I have a real variable "r" and I cannot assign a value of 1/7 to it directly. Here it goes:

main()
{
float r;
r=1/7;
printf("1/7=%.6f\n",r);
getch();
}

This program returns 1/7=0.000000
While the second program with a source code

main()
{
float r,r1;
r1=7;
r=1/r1;
printf("1/7=%.7f\n",r);
getch();
}

returns 1/7=0.142857

So, in C language I cannot assign a value of 1/7 directly? Or am I doing something wrong?

Thank you for help.

[CommonTater]

Try r = 1.0/7.0 and see what happens.

[nerio]

Whaw, it actually works now. Mathematicly there is no reason for it, but probably there is some reason in C. Like you cannot divide two integers but two reals you can I guess. Thank you for help.

[CommonTater]

Whaw, it actually works now. Mathematicly there is no reason for it, but probably there is some reason in C. Like you cannot divide two integers but two reals you can I guess. Thank you for help.

The numeric literals you were using to divide are assumed to be integers. C differentiates by the presence of a decimal point.

And yes you can divide two integers... try the simple 21/7 .... you will get three. BUT when the answer involves decimal points as in 22/7 you will still get 3... whole numbers only. What do you think happens if the answer you get is less than 1 but greater than 0? That's right, you get 0.

[iMalc]

When dividing two integers you get a quotient plus a remainder. In your case the answer comes out at zero, remainder one.

[grumpy]

Whaw, it actually works now. Mathematicly there is no reason for it, but probably there is some reason in C. Like you cannot divide two integers but two reals you can I guess.

Mathematically there is a reason. If computing the ratio of two integers, and the result is also required to be an integer, then some form of truncation or rounding must occur.

In C, when dividing two values of type int, the result will be of type int. That means, mathematically, that truncation or rounding must occur.

Similarly, in C, when dividing two values of type float, the result will be of type float.