Programming in C - Fundamental Study of Strings

Strings
Introduction
Reading and displaying strings
Passing strings to function
String handling functions
C. P. Divate

• Strings are array of characters i.e. they are
arranged one after another in
Thus, a character array is called
characters
memory.
string.
• Each character within the string is stored
within one element of the array successively.
• A string is always terminated by a null
character (i.e. slash zero 0).
Introduction

• Operations performed on
include:
– Reading and writing strings
– Copying one string to another
– Combining strings together
– Comparing strings for equality
– Extracting a portion of a string
character strings
Arrays and Strings…

• A string variable is declared as an array of
characters.
• Syntax:
char string_name[size];
• E.g. char name[20];
• When the compiler assigns a character string
to a character array, it automatically supplies a
null character (‘0’) at the end of the string

• Strings are initialized in either of the following two forms:
char name[4]={‘R’,‘A’,‘M’, ‘0’};
char name[]={‘R’,‘A’,‘M’, ‘0’};
char name[4]=“RAM”;
char name[]=“RAM”;
• When we initialize a character array by listing its
elements, the null terminator or the size of the array
must be provided explicitly.
Initializing String Variables
R A M 0
name[0] name[1] name[2] name[3]

Reading and displaying Strings
• It can be done manually.

String handling functions
• Strings need to be manipulated by
programmer.
• It can be done manually but is time
consuming.

#include <stdio.h>
#include <conio.h>
void main()
{
char input_string[50];
int i=0, length=0;
clrscr();
printf("nEnter your text:t");
gets(input_string);
while(input_string[i]!='0')
{
length++;
i++;
}
printf("nThe length of your text is: %d character(s)", length);
getch();
}
Counting length of the string

#include <stdio.h>
#include <conio.h>
void main()
{
char copy[50], paste[50];
int i;
clrscr();
printf("nEnter your name (to copy):t");
gets(copy);
for(i=0;copy[i]!='0';i++)
{
paste[i]=copy[i];
}
paste[i]='0';
printf("nThe name is (pasted as):t");
puts(paste);
getch();
}
Copying one string to another

• There are various string handling functions
define in string.h some of them are:

void main()
{
char input_string[50];
int length;
clrscr();
printf("nEnter your text:t");
gets(input_string);
length=strlen(input_string);
printf("nThe length of your text is: %d character(s)", length);
getch();
}
14

void main()
{
char copy[50], paste[50];
int i;
clrscr();
printf("nEnter your name (to copy):t");
gets(copy);
strcpy(paste, copy);
printf("nThe name is (pasted as):t");
puts(paste);
getch();
}
15

void main()
{
char first_name[30]=“College " ;
char middle_name[]=" ofApplied";
char last_name[]=" Business";
clrscr();
strcat(first_name,middle_name);
puts(first_name);
strcat(first_name,last_name);
puts(first_name);
getch();
}
16

void main()
{
char str1[30],str2[40];
int diff;
clrscr();
printf("Enter first string:t");
gets(str1);
printf("nEnter second string:t");
gets(str2);
diff=strcmp(str1, str2);
if(diff>0)
printf("n%s is greater than %s by ASCII value difference %d", str1,
str2, diff);
else if(diff<0)
printf("n%s is smaller than %s byASCII value difference %d", str1,
str2, diff);
else
printf("n%s is same as %s", str1, str2);
getch();
}
17

void main()
{
char string[25];
clrscr();
printf("nInput string to be reversed:");
gets(string);
strrev(string);
printf("nThe reversed string is: %s", string);
getch();
}
18

• String is array of characters.
• Thus an array of string is 2-D array of
characters.
• E.g.
char names[5][10];
• Here, names[5][10] means 5 names having 10
characters each.
19
Arrays of Strings

Classwork
• WAPto read name of 5 persons using array of
strings and display them
• WAP to sort name of 5 persons in alphabetical
order

void main()
{
char names[5][10];
int i;
clrscr();
printf("nEnter name of 5 persons:");
for(i=0;i<5;i++)
scanf("%s", names[i]);
printf("nThe names are:");
for(i=0;i<5;i++)
printf("n%s", names[i]);
getch();
}
21

void main()
{
char names[5][10],temp[10];
int i, j;
clrscr();
printf("nEnter name of 5 persons:");
for(i=0;i<5;i++)
gets(names[i]);
for(i=0;i<5;i++)
{
for(j=i+1;j<5;j++)
{
if(strcmp(names[i], names[j])>0)
{
strcpy(temp, names[i]);
strcpy(names[i], names[j]);
strcpy(names[j], temp);
}
}
}
printf("nNames in ascending order:n");
for(i=0;i<5;i++)
puts(names[i]);
getch();
}
22

Programming in C - Fundamental Study of Strings

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