Loops
Saturday, 8 August 2015
Friday, 7 August 2015
if statements in c Language Syntax and E.g
if statement
It is the most simple form
of the branching statements.It takes an expression in parenthesis and an
statement or block of statements. if the expression is true then the statement
or block of statements gets executed otherwise these statements are skipped.
(1) if statement
(2) if else statement
Syntax of if statement:
(1)
if(Condition's)
statement 1
statement 2
....
.....
........
statement n
E.g.1
main()
{
int a=9;
if(a>90)
printf("Hello");
printf("Hi");
printf(" Unique
Programming");
}
Output:
Hi Unique Programming
E.g.2
main()
{
int a=9;
if(a<90)
printf("Hello");
printf("Hi");
printf(" Unique
Programming");
}
Output:
Hello Hi Unique
Programming
(2)
if(Condition's)
{
statement's
}
statement 2
....
.....
........
statement n
E.g.1
main()
{
int a=9;
if(a>90)
{
printf("Hello");
printf("Students");
}
printf("Hi");
printf(" Unique
Programming");
}
Output:
Hi Unique Programming
E.g.2
main()
{
int a=9;
if(a<90)
{
printf("Hello");
printf("
Students");
}
printf("Hi");
printf(" Unique
Programming");
}
Output:
Hello Students Hi Unique
Programming
Syntax of If else
Statement:
(1)
if(Condition's)
statement 1
else
statement 2
....
.....
........
statement n
E.g.1
main()
{
int a=9;
if(a>90)
printf("Hello");
else
printf("Hi");
printf(" Unique
Programming");
}
Output:
Hi Unique Programming
E.g.2
main()
{
int a=9;
if(a<90)
printf("Hello");
else
printf("Hi");
printf(" Unique
Programming");
}
Output:
Hello Unique Programming
(2)
if(Condition's)
{
statement's
}
else
{
statement 's
}....
.....
........
statement n
E.g.1
main()
{
int a=9;
if(a>90)
{
printf("Hello");
printf("Students");
}
else
{
printf("Hi");
printf(" Unique
Programming");
}
}
Output:
Hi Unique Programming
E.g.2
main()
{
int a=9;
if(a<90)
{
printf("Hello");
printf("
Students");
}
else
{
printf("Hi");
printf(" Unique
Programming");
}
}
Output:
Hello Students
Control statements In c Language
C programming Language provides two types of control Statements:
- Branching Statements
- Looping or iterative statements
Branching:
Branching is deciding what actions to take. Branching is so called because the program chooses to follow one branch or another.
(1) if statement
(2) if else statement
(3) Switch statement
(4) Break statement
(5) goto statement
Looping Or Iterative statements:
Looping is deciding how many times to take a certain action.
for
while
do while
Thursday, 6 August 2015
C Language aptitude Questions and answers for TCS, Wipro, DRDO etc Exam
C Language Questions
All the programs are tested
under Turbo C/C++ compilers.
It is assumed that,
Ø Programs run under DOS
environment,
Ø The underlying machine is an
x86 system,
Ø Program is compiled using
Turbo C/C++ compiler.
The program output may
depend on the information based on this assumptions (for example sizeof(int) ==
2 may be assumed).
Predict the output or error(s) for the following:
1. void main()
{
int const * p=5;
printf("%d",++(*p));
}
Answer:
Compiler
error:Cannot modify a constant object.
Explanation:
p
is a pointer to a "constant integer". But we tried to change the
value of the "constant integer".
2. main()
{
char s[
]="man";
int i;
for(i=0;s[
i ];i++)
printf("\n%c%c%c%c",s[
i ],*(s+i),*(i+s),i[s]);
}
Answer:
mmmm
aaaa
nnnn
Explanation:
s[i],
*(i+s), *(s+i), i[s] are all different ways of expressing the same idea.
Generally array name is the base address
for that array. Here s is the base
address. i is the index
number/displacement from the base address. So, indirecting it with * is same as
s[i]. i[s] may be surprising. But in the
case of C it is same as s[i].
3. main()
{
float
me = 1.1;
double
you = 1.1;
if(me==you)
printf("I
love U");
else
printf("I
hate U");
}
Answer:
I
hate U
Explanation:
For
floating point numbers (float,
double, long double) the values
cannot be predicted exactly. Depending on the number of bytes, the precession
with of the value represented varies.
Float takes 4 bytes and long double takes 10 bytes. So float stores 0.9 with
less precision than long double.
Rule of Thumb:
Never
compare or at-least be cautious when using floating point numbers with
relational operators (== , >,
<, <=, >=,!= ) .
4. main()
{
static
int var = 5;
printf("%d
",var--);
if(var)
main();
}
Answer:
5
4 3 2 1
Explanation:
When
static storage class is given, it is
initialized once. The change in the value of a static variable is retained even between the function calls. Main is also treated like any other ordinary function,
which can be called recursively.
5. main()
{
int c[ ]={2.8,3.4,4,6.7,5};
int j,*p=c,*q=c;
for(j=0;j<5;j++) {
printf("
%d ",*c);
++q; }
for(j=0;j<5;j++){
printf("
%d ",*p);
++p; }
}
Answer:
2
2 2 2 2 2 3 4 6 5
Explanation:
Initially
pointer c is assigned to both p and q. In the first loop, since only q is incremented and not c , the value
2 will be printed 5 times. In second loop p
itself is incremented. So the values 2 3 4 6 5 will be printed.
6. main()
{
extern
int i;
i=20;
printf("%d",i);
}
Answer:
Linker Error
: Undefined symbol '_i'
Explanation:
extern
storage class in the following declaration,
extern int i;
specifies
to the compiler that the memory for i
is allocated in some other program and that address will be given to the
current program at the time of linking. But linker finds that no other variable
of name i is available in any other
program with memory space allocated for it. Hence a linker error has occurred .
7. main()
{
int
i=-1,j=-1,k=0,l=2,m;
m=i++&&j++&&k++||l++;
printf("%d
%d %d %d %d",i,j,k,l,m);
}
Answer:
0
0 1 3 1
Explanation
:
Logical
operations always give a result of 1 or
0 . And also the logical AND (&&) operator has higher priority over
the logical OR (||) operator. So the expression
‘i++ && j++ &&
k++’ is executed first. The result of this expression is 0 (-1 && -1 && 0 = 0). Now
the expression is 0 || 2 which evaluates to 1 (because OR operator always gives
1 except for ‘0 || 0’ combination- for which it gives 0). So the value of m is
1. The values of other variables are also incremented by 1.
8. main()
{
char
*p;
printf("%d
%d ",sizeof(*p),sizeof(p));
}
Answer:
1
2
Explanation:
The
sizeof() operator gives the number of bytes taken by its operand. P is a
character pointer, which needs one byte for storing its value (a character).
Hence sizeof(*p) gives a value of 1. Since it needs two bytes to store the
address of the character pointer sizeof(p) gives 2.
9. main()
{
int
i=3;
switch(i)
{
default:printf("zero");
case 1: printf("one");
break;
case 2:printf("two");
break;
case 3: printf("three");
break;
}
}
Answer
:
three
Explanation
:
The
default case can be placed anywhere inside the loop. It is executed only when
all other cases doesn't match.
10.
main()
{
printf("%x",-1<<4);
}
Answer:
fff0
Explanation
:
-1
is internally represented as all 1's. When left shifted four times the least
significant 4 bits are filled with 0's.The %x format specifier specifies that
the integer value be printed as a hexadecimal value.
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