C Programming Language Step by Step Part 5

Operators Precedence in C
Category Operator Associativity
Postfix () [] -> . ++ - - Left to right
Unary + - ! ~ ++ - - (type)* & sizeof Right to left
Multiplicative * / % Left to right
Additive + - Left to right
Shift << >> Left to right
Relational < <= > >= Left to right
Equality == != Left to right
Bitwise AND & Left to right
Bitwise XOR ^ Left to right
Bitwise OR | Left to right
Logical AND && Left to right
Logical OR || Left to right
Conditional ?: Right to left
Assignment = += -= *= /= %=>>= <<= &=
^= |=
Right to left
Comma , Left to right

#include<stdio.h>
void main()
{
int x;
x=-3+4*5-6; printf("%d n",x);
x=3+(4%5)-6; printf("%d n",x);
x=-3*4%-6/5; printf("%d n",x);
x=(7+6)%5/2; printf("%d n",x);
}
11
1
0
1
Program
Output

#include<stdio.h>
void main()
{
int x=2,y,z;
x*=3+2; printf("%d n",x);
x*=y=z=4; printf("%d n",x);
x=y==z; printf("%d n",x);
x==(y=z); printf("%d n",x);
}
10
40
1
1
Program
Output

#include<stdio.h>
void main()
{
int x,y,z;
x=2; y=1; z=9;
x= x&&y||z;
printf("%d n",x);
printf("%d
n",x||!y&&z);
x=y=1;
z=x++ -1;
printf("%d n",x);
printf("%d n",z);
z+=-x ++ + ++y ;
printf("%d n",x);
printf("%d n",z);
}
Program Output
1
1
2
0
3
0

Decision Making
Statement Description
if statement An if statement consists of a boolean expression
followed by one or more statements.
if...else statement An if statement can be followed by an
optional else statement, which executes when
the boolean expression is false.
nested if statements You can use one if or else if statement inside
another if orelse if statement(s).
switch statement A switch statement allows a variable to be tested
for equality against a list of values.
nested switch
statements
You can use one switch statement inside
another switchstatement(s).

if
#include <stdio.h>
int main ()
{
/* local variable definition */
int a = 10;
/* check the boolean condition using if statement */
if( a < 20 )
{
/* if condition is true then print the following */
printf("a is less than 20n" );
}
printf("value of a is : %dn", a);
return 0;
}
Flow Diagram:
1

if...else statement
Syntax:
if(boolean_expression)
{
/* statement(s) will execute if the boolean expression is true */
}
else
{
/* statement(s) will execute if the boolean expression is false */
}
Flow Diagram:
2

#include <stdio.h>
int main ()
{
int a = 100;
/* check the boolean condition */
if( a < 20 )
{
printf("a is less than 20n" );
}
else
{
/* if condition is false then print the following */
printf("a is not less than 20n" );
}
printf("value of a is : %dn", a);
return 0;
}

if...else if...else Statement
Syntax:
if(boolean_expression 1)
{
/* Executes when the boolean expression 1 is true */
}
else if( boolean_expression 2)
{
}
else if( boolean_expression 3)
{
}
else
{
/* executes when the none of the above condition is true */
}
3

Example #include <stdio.h>
int main ()
{
int a = 100;
if( a == 10 )
{
printf("Value of a is 10n" );
}
else if( a == 20 )
{
/* if else if condition is true */
}
else if( a == 30 )
{
/* if else if condition is true */
}
else
{
/* if none of the conditions is true */
printf("None of the values is matchingn" );
}
printf("Exact value of a is: %dn", a );
return 0;
}

nested if statements4
Syntax:
if( boolean_expression 1)
{
if(boolean_expression 2)
{
}
}

Example
#include <stdio.h>
int main ()
{
int a = 100;
int b = 200;
if( a == 100 )
{
/* if condition is true then check the following
*/
if( b == 200 )
{
printf("Value of a is 100 and b is 200n" );
}
}
printf("Exact value of a is : %dn", a );
printf("Exact value of b is : %dn", b );
return 0;
}

switch statement
Syntax: switch(expression){
case constant-expression :
statement(s);
break; /* optional */
case constant-expression :
statement(s);
break; /* optional */
/* you can have any number of case statements */
default : /* Optional */
statement(s);
}
switch ( integer expression )
{
case constant 1 :
do this ;
case constant 2 :
do this ;
case constant 3 :
do this ;
default :
do this ;
}
5

Example
#include <stdio.h>
int main ()
{
char grade = 'B';
switch(grade)
{
case 'A' :
printf("Excellent!n" );
break;
case 'B' :
case 'C' :
printf("Well donen" );
break;
case 'D' :
printf("You passedn" );
break;
case 'F' :
printf("Better try againn" );
break;
default :
printf("Invalid graden" );
}
printf("Your grade is %cn", grade );
return 0;
}

nested switch statements
Syntax:
switch(ch1) {
case 'A':
printf("This A is part of outer switch" );
switch(ch2) {
case 'A':
printf("This A is part of inner switch" );
break;
case 'B': /* case code */
}
break;
case 'B': /* case code */
}
6

Example
#include <stdio.h>
int main ()
{
int a = 100;
int b = 200;
switch(a) {
case 100:
printf("This is part of outer switchn", a );
switch(b) {
case 200:
printf("This is part of inner switchn", a );
}
}
printf("Exact value of a is : %dn", a );
printf("Exact value of b is : %dn", b );
return 0;
}

C Programming Language Step by Step Part 5

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C Programming Language Step by Step Part 5