Sunday, 5 March 2017

String functions in C/C++ Program

String functions
String functions are defined in the string.h header file. These functions are used to manipulate the strings as defined. The important functions of string.h are strcpy(), strcat(), strlen(), strcmp(), strcmpi(), strev(), strupur() and strlwr(). The use of these functions are given below:

strcpy()- to copy one string to another
strcat()- to concatenate two strings into one
strlen()- to return length of string
strcmp()- to compare two strings for equality
strcmpi()- to comaper two string without case sensitivity
strev()- to return reverse of the string
strupur()- to return uppercase string for lowercase string
strlwr()- to return lowercase string for uppercase string

To understand the use of above functions, let consider the given example:
 
Example program to show the use of string functions

#include<iostream.h>
#include<conio.h>
#include<string.h>
void main()
{
 char s1[20],s2[20],i;
 clrscr();
 cout<<"Enter the string to find the length:";
 cin>>s1;
 cout<<"\nLength of the string is..."<<strlen(s1);

 strcpy(s2,s1);
 cout<<"\n\nCopied string is..."<<s2;

 cout<<"\n\nEnter 2 strings to be concatenated:";
 cin>>s1>>s2;
 strcat(s1,s2);
 cout<<"\nConcatenated string is..."<<s1<<endl;

 cout<<endl<<"\nEnter 2 strings to be compared:";
 cin>>s1>>s2;
 i=strcmp(s1,s2);
 if(i==0)
  cout<<"\nBoth strings are equal\n";
 else if(i<0)
  cout<<s1<<" is less than "<<s2<<endl;
 else
  cout<<s1<<" is greater than "<<s2;

 cout<<"\n\nEnter the string to change into lower case:";
 cin>>s1;
 cout<<"\nLower case of the given string is..."<<strlwr(s1);

 cout<<"\n\nEnter the string to change into upper case:";
 cin>>s1;
 cout<<"\nUpper case of the given string is..."<<strupr(s1);

 cout<<"\n\nEnter the string to be reversed:";
 cin>>s1;
 cout<<"\nThe reversed string is..."<<strrev(s1);

}
Output of Example program 
 Enter the string to find the length: welcome
 Length of the string is...7

 Copied string is...welcome;

 Enter 2 strings to be concatenated: raj
 kumar

 Concatenated string is... rajkumar

 Enter 2 strings to be compared: tata
 bata
 tata is greater than bata

 Enter the string to change into lower case: WELCOME
 Lower case of the given string is...welcome

 Enter the string to change into upper case: computer
 Upper case of the given string is...COMPUTER

 Enter the string to be reversed: TAJ
 The reversed string is...JAT

 
Example menu-driven program to show the use of string functions
#include<stdio.h>
#include<string.h>
main()
{
    int a,b;
    char s1[100],s2[100];
    cout>>"Enter a string.\n";
    cin>>s1;
   
    cout>>”Enter the operation you wish to perform on the string:
\n1. String Length\n2. String Reverse\n3. String Concatenation
\n4. String Copy\n5. String Upper Case\n6. String Lower Case
\n7. String Comparison\n";
   
    cin>>a;

    switch(a)
    {
    case 1:
        {
            b=strlen(s1);
            cout<<"String Length = ”<<b;
            break;
        }
    case 2:
        {
            cout<<"String Reverse: ”<<strrev(s1);
            break;
        }
    case 3:
        {
            cout<<"Enter the target string.\n";
            cin>>s2;
            strcat(s2,s1);
            cout<<"Result - "<<s2;
            break;
        }
    case 4:
        {
            strcpy(s2,s1);
            cout<<"Copied String - "<<s2;
            break;
        }
    case 5:
        {
            cout<<"The Upper Case of String is "<<strupr(s1);
            break;
        }
    case 6:
        {
            cout<<"The Lower Case of String is "<<strlwr(s1);
            break;
        }
    case 7:
        {
            cout<<"Enter the string you wish to compare with the previous string.\n";
            cin>>s2;
            a=strcmp(s1,s2);
            cout<<"String Compare "<<a;
            break;
        }

    default:
        {
            cout<<"You have not entered a valid option.";
        }
    }


}

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