C Programming Language

1. Part 11
Rumman Ansari
string

2. C Programming String
1. array of character are called strings
2. The string in C programming language is actually a one-dimensional array of
characters
array of characters which is terminated by a null character '0'

3. Declaration and initialization
char greeting[6] = {'H', 'e', 'l', 'l', 'o', '0'};
char greeting[] = "Hello";
Data_type string_name [ ];
char s[5];

4. Reading Strings from user.
char c[20];
scanf("%s",c);
Print Strings from user.
char name[20];
printf("%s",name);

5. #include <stdio.h>
int main ()
{
char greeting[6] = {'H', 'e', 'l', 'l', 'o', '0'};
printf("Greeting message: %sn", greeting );
return 0;
}
Example

6. Write a C program to illustrate how to read string from terminal.
#include <stdio.h>
int main(){
char name[20];
printf("Enter name: ");
scanf("%s",name);
printf("Your name is %s.",name);
return 0;
}

7. C program to read line of text manually.
#include <stdio.h>
int main(){
char name[30],ch;
int i=0;
printf("Enter name: ");
while(ch!='n') // terminates if user hit enter
{
ch=getchar();
name[i]=ch;
i++;
}
name[i]='0'; // inserting null character at end
printf("Name: %s",name);
return 0;
}

8. #include <stdio.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;
}
There are predefined functions gets() and puts() in C language to read and
display string respectively.

9. S.N. Function & Purpose
1 strcpy(s1, s2);Copies string s2 into string s1.
2 strcat(s1, s2);Concatenates string s2 onto the end of string s1.
3 strlen(s1);Returns the length of string s1.
4 strcmp(s1, s2);Returns 0 if s1 and s2 are the same; less than 0 if s1<s2;
greater than 0 if s1>s2.
5 strchr(s1, ch);Returns a pointer to the first occurrence of character ch in
string s1.
6 strstr(s1, s2);Returns a pointer to the first occurrence of string s2 in string
s1.
strlwr() Converts string to lowercase
strupr() Converts string to uppercase

10. #include <stdio.h>
#include <string.h>
int main ()
{
char str1[12] = "Hello";
char str2[12] = "World";
char str3[12];
int len ;
/* copy str1 into str3 */
strcpy(str3, str1);
printf("strcpy( str3, str1) : %sn", str3 );
/* concatenates str1 and str2 */
strcat( str1, str2);
printf("strcat( str1, str2): %sn", str1 );
/* total lenghth of str1 after concatenation */
len = strlen(str1);
printf("strlen(str1) : %dn", len );
return 0;
}

11. C Program to Find the Frequency of Characters in a String
#include <stdio.h>
int main(){
char c[1000],ch;
int i,count=0;
printf("Enter a string: ");
gets(c);
printf("Enter a character to find frequency: ");
scanf("%c",&ch);
for(i=0;c[i]!='0';++i)
{
if(ch==c[i])
++count;
}
printf("Frequency of %c = %d", ch, count);
return 0;
}

12. C Program to Find the Number of Vowels, Consonants, Digits and White space
in a String
#include<stdio.h>
int main(){
char line[150];
int i,v,c,ch,d,s,o;
o=v=c=ch=d=s=0;
printf("Enter a line of string:n");
gets(line);
for(i=0;line[i]!='0';++i)
{
if(line[i]=='a' || line[i]=='e' || line[i]=='i' || line[i]=='o' || line[i]=='u' || line[i]=='A' || line[i]=='E' || line[i]=='I' || line[i]=='O' || line[i]=='U')
++v;
else if((line[i]>='a'&& line[i]<='z') || (line[i]>='A'&& line[i]<='Z'))
++c;
else if(line[i]>='0'&&c<='9')
++d;
else if (line[i]==' ')
++s;
}
printf("Vowels: %d",v);
printf("nConsonants: %d",c);
printf("nDigits: %d",d);
printf("nWhite spaces: %d",s);
return 0;
}

13. C Program to Remove all Characters in a String except alphabet
#include<stdio.h>
int main(){
char line[150];
int i,j;
printf("Enter a string: ");
gets(line);
for(i=0; line[i]!='0'; ++i)
{
while (!((line[i]>='a'&&line[i]<='z') || (line[i]>='A'&&line[i]<='Z' || line[i]=='0')))
{
for(j=i;line[j]!='0';++j)
{
line[j]=line[j+1];
}
line[j]='0';
}
}
printf("Output String: ");
puts(line);
return 0;
}