This document summarizes key concepts in C programming including formatted input, formatted output, expressions, and operator precedence. It explains that input and output must be formatted to specify where values are stored in memory. Expressions combine variables, operators, and constants, and are evaluated based on precedence rules. Parentheses, multiplication/division, and addition/subtraction have the highest to lowest precedence. Examples demonstrate how expressions are evaluated based on these rules.

1. Fundamentals of Computing And C Programming
Unit - II - Basics of C Language

2. Seminar 3
By Karthik Srini

3. Presentation By, Karthik Srini
Synopsis
• Formatted Input
• Formatted Output
• Expressions
• Precedence of Operators

4. Formatted Input
C Language

5. Presentation By, Karthik Srini
Formatted Input
While accepting values from the user, the compiler must be instructed
with the memory location in which the input values must be stored.
This must be in a specified format.
For example,
If two integers, say n1 and n2 are to be got from the user, then,
scanf(“%d%d”,&n1,&n2);

6. Presentation By, Karthik Srini
Formatted Input - Points to remember
•Format specifications contained in the control string should match the
arguments in order
•Input data items must be separated by space and must match the
variable receiving the input in same order.
•The reading will be terminated, when scanf() encounters a mismatch
of data or a character that is not valid for the value being read.

7. Formatted Output
C Language

8. Presentation By, Karthik Srini
Formatted Output
In a similar manner, output also must be given in such a way that, it is
easy to understand.
For example,
If one integer and one float value are to be printed, then,
printf(“%d%f”,n,m);

9. Presentation By, Karthik Srini
Expressions

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Expressions
An expression is defined as the collection of variables, operators and
constants.
For example,
x = 5 + num2 - 15 ;

11. Presentation By, Karthik Srini
Operator Precedence

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Operator Precedence
The hierarchy that is followed while an expression is evaluated is
called operator precedence.

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Rules for Evaluation of expression
➢First , parenthesised sub expression from left to right are
evaluated.
➢If parentheses are nested, the evaluation begins with the
innermost sub-expression.
➢The precedence rule is applied in determining the order
of application of operators in evaluating sub-expressions.
➢The associativity rule is applied when two or more
operators of the same precedence level appear in a sub-
expression.
➢Arithmetic expressions are evaluated from left to right
using rules of precedence.
➢When parentheses are used, the expression within
parentheses assume highest priority

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Example

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Example
If x=10 and y=5 ;
What is ( x * y ) - ( x / y ) ; ?
Answer :
( 50 ) - ( 2 ) = 48

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Exercise
If a = 9 , b = 12 , c = 3 . Then evaluate the following :
( i ) x = a - b / 3 + c * 2 - 1 ;
( ii ) y = a - b / ( 3 + c ) * ( 2 - 1 ) ;
( iii ) z = - a + ( ( b / 3 + c ) * 2 ) - 1;

18. Presentation By, Karthik Srini
Answers
( i ) x = 10
( ii ) y = 7
( iii ) z = 4

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Queries???

20. Presentation By, Karthik Srini
Thank You