Implicit data type conversion in C

Question

int a=98, b=10;
float c;
c=a/b;

Output: c=9

I know because of implicit type conversion, c value is 9 not 9.8 but then I encountered this question:

int a,b,c,d;
a=40;
b=35;
c=20;
d=10;
printf("%d",a*b/c-d);

output: 60

Now if we see the precedence for equation is right to left and according to BODMAS rule b/c(35/20) will be performed first so 35/20 = 1.75 and then implicit conversion to integer make it to 1 and then rest will follow up the answer must be 30 but the output is 60 which is correct answer. Can you explain me why?

Operator precedence for * and / in C is left-to-right: http://en.cppreference.com/w/c/language/operator_precedence So `a*b` will be done first. It,s equivalent to writing `((a*b)/c)-d`. (wrote as answer) — AntonH, Jun 29 '17 at 20:17
Ref [BODMAS](https://en.wikipedia.org/wiki/Order_of_operations#Mnemonics) — chux - Reinstate Monica, Jun 29 '17 at 20:18
`35/20 = 1.75` is not so here as it is `int` math. `35/20` --> 1. IAC, the `40*35` happens first like `((a*b)/c)-d` using only `int` math and no type conversions. — chux - Reinstate Monica, Jun 29 '17 at 20:20
Ah... another victim of this stupid abbreviation, seeing `D` comes before `M`... — Eugene Sh., Jun 29 '17 at 20:24
@AntonH Any of these are harmful. Just take a look at all of these "holy" wars on the social media because of not understanding this stuff. It's really not that hard to memorize the rules without using these acronyms. — Eugene Sh., Jun 29 '17 at 20:36
The first part of the question is unrelated to the second part — and you don't even ask a question about the `c = a / b;` expression. It should really be removed from the question. — Jonathan Leffler, Jun 29 '17 at 23:12

score 1 · Answer 1 · answered Jun 29 '17 at 20:20

1

Operator precedence in C for * and / in C is left-to-right: http://en.cppreference.com/w/c/language/operator_precedence

So a*b will be done first. It's equivalent to writing ((a*b)/c)-d.

answered Jun 29 '17 at 20:20

AntonH

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score 0 · Answer 2 · answered Jun 29 '17 at 21:37

0

So your execution will follow left to right execution for / and *:

((40 * 35) / 20) - 10 = ((1400) / 20) - 10 = (70) - 10 = 60

answered Jun 29 '17 at 21:37

unalignedmemoryaccess

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Implicit data type conversion in C

2 Answers2