String Functions

 

The string functions can analyze and transform null terminated strings.  In order to manipulate null terminated strings header file <cstring> is included in the program. This header file provides the same functionality as string.h in C. Some of the commonly used string functions are: -

 

 

Here is a program which illustrates the working of string functions.

 

#include<iostream>

#include<cstring>

using namespace std;

 

int main ()

{

      int l;

      char name[40]=" Tom is a good boy";

      char name1[40]="Mary is a good girl";

      char stri[40];

      l=strlen(name);

      cout << "The lenght of the string 1 is : " << l <<  endl;

      if(strstr(name,"good"))

      {

                  cout << "Substring good appears in string 1 " << endl;

      }

      if(strchr(name1,'M'))

      {

                  cout << "Character M appears in sting 1 " <<  endl;

      }

      if(strcmp(name,name1)>0)

      {

                  cout << "String 2 appears after string" << endl;

      }

      strcpy(stri,name1);

      cout << "The copied string  : " << stri << endl;

      strncat(stri,name,4);

      cout << " The modified string : " << stri << endl;

      if(strncmp(stri,name1,3)==0)

      {

                  cout << "First 3 characters of two strings are equal" << endl;

      }

      strcat(name,"  ");

      strcat(name,name1);

      cout << name << endl;

      return(0);

     

}

 

The result of the program is:-

 

program output

 

The statement

 

#include<cstring>

 

includes a header file <cstring> into the program. The statement

 

       l=strlen(name);

 

computes the length of the string name. The function strlen(name)  returns the length of the string name. The length of the string is 18. The statement

 

      if(strstr(name,"good"))

 

checks whether substring “good” appears in the string name. The function strstr(name,”good”) returns true as “good” appears in string name. The statement

     

      if(strchr(name1,'M'))

 

checks whether character ‘M’ appears in string name1. The function strchr(name1,’M’) returns true as character ‘M’ appears in string name1. The statement

 

                        if(strcmp(name,name1)>0)

 

compares two strings name and name1. It returns false as string name< string name1.

The statement

 

      strcpy(stri,name1);

 

copies content of string name1 into string stri. The statement

 

            strncat(stri,name,4);

 

concatenates first 4 letters of string name to string stri. The statement

 

            if(strncmp(stri,name1,3)==0)

     

compares first  3 characters of string name1 with first 3 characters of string stri. It   returns true as first 3 characters of name1 and stri are same. The statement

 

      strcat(name,"  ");

 

concatenates whitespace at the end of the string name. The statement

 

            strcat(name,name1);

 

concatenates content of string name1 at the end of  string name.

 

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