macOS Help in C Arithmetics

uaecasher

macrumors 65816

Original poster

• Jun 15, 2009

• #1

Hello,

i have written this code:

Code:

#include <stdio.h> 
int main (void) 
{ 
	
	int a = 15;
	int b = 35;
	
	
printf("a / b * b = %i\n", a / b * b);

	
}

the result i get is zero, but it should be 15, why I'm getting a 0

thanks

 

4409723

Suspended

• Jun 15, 2009

• #2

You need to think about the order this is being evaluated, see: http://www.difranco.net/cop2220/op-prec.htm

a / b * b becomes (a / b) * b

where:
a = 15;
b = 35;

(15/35)*35
0*35

Remember these are integers so 15/35 will be 0. If you want to get the fractional part you'll need to use floats or doubles.

 

E

EMT

macrumors newbie

• Jun 15, 2009

• #3

Use parenthesis in your expressions to make it safe.:

 

S

Sander

macrumors 6502a

• Jun 16, 2009

• #4

EMT said:

Use parenthesis in your expressions to make it safe.:

Click to expand...

That wouldn't help in this case - it's the integer division that's the problem here.

 

gnasher729

Suspended

• Jun 16, 2009

• #5

uaecasher said:

Hello,

i have written this code:

Code:

#include <stdio.h> 
int main (void) 
{ 
	
	int a = 15;
	int b = 35;
	
	
printf("a / b * b = %i\n", a / b * b);

	
}

the result i get is zero, but it should be 15, why I'm getting a 0

thanks

Click to expand...

It should be zero. Buy a C book for beginners.