C PROGRAMMING
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S |
tring:-
String is a collection of character type data.
In other words character arrays are called string. In C programming the group
of characters,digits, and symbols enclosed within quotation marks are called as
string.Every string is terminated with string ‘\0’(NULL) character. The
Null character is a byte with all bits at logic zero. Hence its decimal value
is zero. It is not compulsory to write ‘\0’ in string. The compiler
automatically puts ‘\0’ at the end of the character array(string). Every
character of string store in contiguous memory locations. Each character of string occupies 1 byte of
memory.
char
nm[5];
|
A |
B |
H |
I |
\0 |
nm[0] nm[1] nm[2] nm[3] nm[4]
or
char
name[ ]= {‘I’, ‘N’ ,’ D’ , ’I’ , ‘A’ ,’\0’};
char
text[]= “HAVE A NICE DAY”;
(Initialization of NULL character is not
essential.)
character
array can be initialized as follows:-
(a)
char name[6]={‘p’
, ’a’ , ’n’ , ’k’ ,’a’ , ’j’ };
(b)
char name[6]={‘p’
, ’a’ , ’n’ , ’k’ ,’a’ , ’j’ };
Here , in case (a) the output will not be ‘pankaj’ but
it contains some garbage value. Arguments in this example are initialized with
6, which is exactly equal to a number of characters inside the braces. The Null
character must be included and hence, the argument must be [7] instead of [6].
Example:-
#include <stdio.h>
#include<conio.h>
void main()
{
char name1[6]={‘p’
, ’a’ , ’n’ , ’k’ ,’a’ , ’j’ };
char name2[7]={‘p’ , ’a’ , ’n’ , ’k’ ,’a’ ,
’j’ };
clrscr();
printf(“name1=%s”,name1);
printf(“name2=%s”,name2);
}
Output
:- pankajpankaj
pankaj
Here
null character has not been considered in the first statement.
Declaration
of string in different formate:-
char
arr1[9]={‘W’, ‘E’, ‘L ’, ‘ ’, ‘C
’, ‘ O’, ‘ M’, ‘ E ’, ‘ \0 ’ }
char
arr2[9]=”WELCOME”
char
arr3[9]={{‘W’},{‘E’},{‘L’},{‘ ’},{‘C’},{‘O’},{‘M’},{’E’}};
printf(“\n
Array1=%s”,arr1);
printf(“\n
Array2=%s”,arr2);
printf(“\n
Array3=%s”,arr3);
(Here,
above all print welcome)
*Display
of strings:-
The
printf() function with %s format is to be used for displaying the string on
screen.
printf(“%s
\n”,nm ); PRABHAKAR
printf(“%.5s
\n”nm); prabh.
***
How to read string form terminal***
#include<stdio.h>
int
main()
{
char name[20];
printf(“Enter Name”);
scanf(“%s”,name);
printf(“your name is %s”,name);
return
0;
}
Output:-
Enter name: Abhishek kumar.
Your name is: Abhishek
(Here
program will ignore kumar because, scanf() takes only string before the white
space).
//Prg
to reading a line of text*/
#include<stdio.h>
#include<conio.h>
int
main()
{
char name[30],ch;
int
i=0;
printf(“\n
Enter name”);
while(ch!=’\n’)
{
ch=getchar();
name[i]=ch;
i++;
}
name[i]=’\0’;
printf(“Name=%s”,name);
return 0;
}
(Here
, The process to take string is tedious. There are predefined function gets()
and puts in c language to read and display string respectively.)
#include<stdio.h>
#include<conio.h>
int main()
{
char name[30];
printf(“Enter name”);
gets(name);//Function
to read string from user.
printf(“Name:-”);
puts(name);//Function to display string.
return (0);
}
(Both
above program has same output.)
Enter name: Abhi kr.
Name:- Abhi
kr.
//**There are some example(program) related with string.
//prg to count white space in given
text
#include<stdio.h>
#include<conio.h>
int main()
{
char nm[20];
int i,c=0;
printf("Enter char ");
//scanf("%s",nm);
gets(nm);
for(i=0;nm[i]!='\0';i++)
{
if(nm[i]==' ')
c=c+1;
}
puts(nm);
printf("\n total white space= %d",c);
getch();
return 0;
}
//prg to count total length of given text
#include<stdio.h>
#include<conio.h>
int main()
{
char nm[20];
int i,c=0;
printf("Enter char ");
//scanf("%s",nm);
gets(nm);
for(i=0;nm[i]!='\0';i++)
{
c=c+1;
}
puts(nm);
printf("\n total white space= %d",c);
getch();
return 0;
}
//prg
to count total vowel , consonent and white space
#include<stdio.h>
#include<conio.h>
int main()
{
char nm[20];
int i,vol=0,space=0,consonent=0;
printf("Enter char ");
//scanf("%s",nm);
gets(nm);
for(i=0;nm[i]!='\0';i++)
{
if(nm[i]=='a' || nm[i]=='A'|| nm[i]=='e' ||nm[i]=='E'||nm[i]=='o'
||nm[i]=='O'||nm[i]=='u'|| nm[i]=='U'||nm[i]=='i'||nm[i]=='I')
vol++;
else if(nm[i]==' ')
space++;
else
consonent++;
}
puts(nm);
printf("\n total Vowel= %d",vol);
printf("\n total space =%d",space);
printf("\n total consonent=%d",consonent);
getch();
return 0;
}
Call by Value
and Reference
There are
two ways in which we can pass arguments to the function.
(1). Call by Value:-
In this type value of actual arguments are
passed to the formal arguments and the operation is done on the formal
arguments. Any change made in the formal argument does not effect the actual
argument because formal arguments are photocopy of actual arguments. Hence,
when function is called by the call or value method , it does not affect the
actual contents of the actual arguments. Changes made in the formal arguments
are local to the block of the called function. Once control returns to the
calling function the changes made vanish.
Now
we try to understand through program.
#include<stdio.h>
#include<conio.h>
int
main()
{
void
swap(int,int);
clrscr();
int
x,y;
printf("\n
enter value of x and y");
scanf("%d
%d",&x,&y);
swap(x,y);//Actual
Argument
printf("\n
in main() X=%d y=%d",x,y);
return
0;
}
void
swap(int a,int b)//Formal Argument
{
int k;
k=a;
a=b;
b=k;
printf("\n change function x=%d y=%d",a,b);
}
outpur:-
Enter values of x
and y: 10 20
After swap x=20
y=10
in main x=10 y=20
(2)Call By reference:-
In
call by reference instead of passing values, addresses(reference)are passed. In
call by reference method function
operates on addresses rather than values. Here formal arguments are pointers to
the actual arguments and formal arguments points to the actual argument. Hence
changes made in the arguments are permanent.
//Write
a program to send a value by reference.
#include<stdio.h>
#include<conio.h>
int main()
{
int x,y;
swap(int* , int*) ;
clrscr();
printf("\n Enter values of x and y");
scanf("%d %d",&x,&y);
swap(&x,&y);
printf("\n in main() x=%d y=%d",x,y);
return 0;
}
swap(int *a , int *b)
{
int *k;
*k=*a;
*a=*b;
*b=*k;
printf("\n in swap() x=%d
y=%d",*a,*b);
}
Output:-
Enter
no in x & y. 10 20
In swap()
x=20 y=10
In main() x=20 y=10.
Pointer:-
Variable are used in C to hold data
values during the execution of a program. Every variable when declared occupies
certain memory location. In c it is possible to access and display the address
of memory location of variable using & operator with variable name.
Pointer is a memory variable that stores
a memory address of another variable. Pointer name is as same as variable name
but it always denoted or preceded by “*” operator.
Advantage of pointer.
1. ( Pointers save the
memory space.
2.
Pointer is faster because data is manipulated with
the address i.e. direct access to memory location.
3.
The memory is
accessed efficiently with the pointer
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