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What are Strings?

The string is an object of the string class and it is defined in the header file i.e. <string.h>.The string class has many constructors that are called to create a string object.
It represents the sequence of characters. The operations which can be performed on strings are comparison, concatenation, conversion, etc.
The one dimensional or single dimensional array of characters is known as Strings and is terminated by null character ‘\0’.

For example,

‘Hello’ is a string of 5 characters.

How to define strings in C++?

As in C programming, the collection of characters is stored in the form of arrays and they are supported by C++ programming too. They are known as C-strings. The C-strings arrays are of char type and is terminated by null (\0) character. So, let us see how strings are defined in C++.

For example:

char str_arr[ ] = “Hello”;

In the above code you can see that, str_arr is a string and it contains 6 characters. In the C++ programming language, the array holds the null character value which is added to the end of the string automatically.

Let us have a look at the example:

#include<iostream>
using namespace std; 
 int main( )
 
 { char str_arr[ ] = "Hello";
 
 cout<<str_arr;

return 0;
 
 }

#include<iostream>

using namespace std;

int main( )

{ char str_arr[ ] = "Hello";

cout<<str_arr;

return 0;

}

Functions in Strings

C++has a wide range of functions that manipulate the strings. Let us have a look on them:

strcat:

It is a string concatenate function. It will concatenate or join the second string with the first string at the end.

Let us have a look at the example:

#include<iostream>
 #include<cstring>

using namespace std;
 
 int main( )
 
 { char s1[10] = "Hello";
 
 char s2[30] = "Good Morning";
 
 strcat(s1,s2);
 
 cout<<"The new string after concatenation is:" <<s1<<endl;
 
 return 0;
 
 }

#include<iostream>

#include<cstring>

using namespace std;

int main( )

{ char s1[10] = "Hello";

char s2[30] = "Good Morning";

strcat(s1,s2);

cout<<"The new string after concatenation is:" <<s1<<endl;

return 0;

}

strcpy:

It is a string copy function. It will copy the first string into second string.

Let us have a look at the example:

#include<iostream> 
 #include<cstring>
 using namespace std;
 int main( )
 
 { char s1[10] = "Hello";
 
 char s2[10];
 
 strcpy(s2,s1); //copy the first string in second string
 
 cout<<"The new string is:"<<s2<<endl;
 
 return 0;
 
 }

#include<iostream>

#include<cstring>

using namespace std;

int main( )

{ char s1[10] = "Hello";

char s2[10];

strcpy(s2,s1); //copy the first string in second string

cout<<"The new string is:"<<s2<<endl;

return 0;

}

strcmp:

It is a string compare function. In this function it compares the two strings if the strings are equal it will return 0 or else if the strings are not equal it will return 1.

Let us have a look at the example:

#include<iostream>
#include<cstring>
using namespace std;
 
int main()
 
{
 
 char s1[10] = "Hello", s2[10] = "morning";
 
 cout<<"\nEnter first string : "<<s1;
 
 cout<<"\nEnter second string : "<<s2;
 
 if(strcmp(s1, s2)==0)
 
 { cout<<"\nThe strings are equal";
 
 }
 
 else
 
 { cout<<"\nThe strings are not equal";
 
 }
 
 return 0;
 
}

#include<iostream>

#include<cstring>

using namespace std;

int main()

{

char s1[10] = "Hello", s2[10] = "morning";

cout<<"\nEnter first string : "<<s1;

cout<<"\nEnter second string : "<<s2;

if(strcmp(s1, s2)==0)

{ cout<<"\nThe strings are equal";

}

else

{ cout<<"\nThe strings are not equal";

}

return 0;

}

strlen:

It is a string length function. It will return the length of a string.

Let us have a look at the example:

#include<iostream>
 
 #include<cstring>
 using namespace std;
 int main( )
 
 { char s1[10] = "Hello";
 
 int length;
 
 length= strlen(s1); //it provide the length of the string
 
 cout<<"The length of string is:" <<length<<endl;
 
 return 0;
 
 }

#include<iostream>

#include<cstring>

using namespace std;

int main( )

{ char s1[10] = "Hello";

int length;

length= strlen(s1); //it provide the length of the string

cout<<"The length of string is:" <<length<<endl;

return 0;

}

strchr:

In this it will take the two arguments string and character. It will searches for the character from the given string.

Let us have a look at the example:

#include <iostream>

#include <cstring>

using namespace std;

int main()

{

char s1[ ] = "Hello World";

char ch = 'l';

if (strchr(s1, ch))

cout << ch << " is present in the string \"" << s1 << "\"";

else

cout << ch << " is not present in the string \"" << s1 << "\"";

return 0;

}

#include <iostream>

#include <cstring>

using namespace std;

int main()

{

char s1[ ] = "Hello World";

char ch = 'l';

if (strchr(s1, ch))

cout << ch << " is present in the string \"" << s1 << "\"";

else

cout << ch << " is not present in the string \"" << s1 << "\"";

return 0;

}

strstr:

It will take two arguments string and destination. It will search the first occurrence of string in the first string.

Let us have a look at the example:

#include <iostream>
 
#include <cstring>
 using namespace std;
int main()
 
{
 
 char s1[ ] = "Hello World";
 
 char destination[ ] = "World";
 
 char *p = strstr(s1, destination);
 
 if (p)
 
 cout << "'" << destination << "' is present in the string \"" << s1 << "\" at position" << p-s1;
 
 else
 
 cout << destination << "is not present in the string\"" << s1<< "\"";
 
 return 0;
 
}

#include <iostream>

#include <cstring>

using namespace std;

int main()

{

char s1[ ] = "Hello World";

char destination[ ] = "World";

char *p = strstr(s1, destination);

if (p)

cout << "'" << destination << "' is present in the string \"" << s1 << "\" at position" << p-s1;

else

cout << destination << "is not present in the string\"" << s1<< "\"";

return 0;

}

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